Golf balls comprising highly-neutralized acid polymers

ABSTRACT

A golf ball comprising an inner core formed of a first material and comprising i) a central portion; and ii) a plurality of spaced projections extending radially outward from the central portion forming gaps between each projection, and each projection having an enlarged free end and a substantially conical shape; an outer core formed of a second material, said second material being disposed within the gaps and the recesses to form a core; and a cover layer; wherein at least one of the first and second materials comprises a polymer containing an acid group neutralized by an organic acid or a salt thereof, the organic acid or salt thereof being present in an amount sufficient to neutralize the polymer by at least about 100%.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Application Ser. No.10/118,719, filed Apr. 9, 2002, now U.S. Pat. No. 6,756,436, which is anon-provisional application claiming priority to U.S. ProvisionalApplication Ser. No. 60/301,046, filed Jun. 26, 2001.

FIELD OF THE INVENTION

The present invention is directed to golf ball compositions and, inparticular, polymer compositions including highly-neutralized polymersand blends thereof.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solidand wound. Solid golf balls include one-piece, two-piece (i.e., solidcore and a cover), and multi-layer (i.e., solid core of one or morelayers and/or a cover of one or more layers) golf balls. Wound golfballs typically include a solid, hollow, or fluid-filled center,surrounded by a tensioned elastomeric material, and a cover. It is alsopossible to surround a hollow or fluid-filled center with a plurality ofsolid layers. Solid balls have traditionally been considered longer andmore durable than wound balls, but many solid constructions lack the“feel” provided by the wound construction.

More recently, by altering ball construction and composition,manufacturers have been able to vary a wide range of playingcharacteristics, such as compression, velocity, “feel,” and spin,optimizing each or all be optimized for various playing abilities. Inparticular, a variety of core and cover layer(s) constructions, such asmulti-layer balls having dual cover layers and/or dual core layers, havebeen investigated and now allow many non-wound balls to exhibitcharacteristics previously maintainable in a solid-construction golfball. These golf ball layers are typically constructed with a number ofpolymeric compositions and blends, including polybutadiene rubber,polyurethanes, polyamides, and ethylene-based ionomers.

Ionomers, and in particular ethylene α,β-ethylenically unsaturatedcarboxylic acid copolymers or a melt processible ionomer thereof, are apreferred polymer for many golf ball layers. One problem encounteredwith the use of ionomers as stiff layers, however, is theunprocessability of the material as the percent of neutralization of theacid group increases. Ionomers are stiffened by increasing the amount ofneutralization by a metal cation or a salt thereof. Once the percent ofneutralization is greater than about 60% (depending on metal cationselected), the melt flow of the ionomer becomes too low and the ease ofprocessablilty decreases or disappears altogether. For tri-valentcations, the percent neutralization at which the polymer becomesunprocessable can be significantly lower.

There is a need, therefore, for ionomer compositions that areneutralized at high percentages, but in a manner that still allowsresultant polymer compositions to be processible. The present inventiondescribes such compositions and there use in a variety of golf ball coreand cover layers.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball comprising a corecomprised of a polymer containing an acid group neutralized by anorganic acid or a salt thereof, the organic acid or salt thereof beingpresent in an amount sufficient to neutralize the polymer by at leastabout 80%, wherein the core has a first Shore D hardness, a compressionof no greater than about 80, and a diameter of no less than about 1.53inches; and a cover comprised of a material having a second Shore Dhardness at least 10 points less than the first hardness.

Additionally, the present invention is also directed to a golf ballcomprising a core comprised of a polymer containing an acid groupneutralized by an organic acid or a salt thereof, the organic acid orsalt thereof being present in an amount sufficient to neutralize thepolymer by at least about 80%, wherein the core has a first Shore Dhardness, a compression of no greater than about 80, and a diameter ofno less than about 1.53 inches; and a cover comprised of a materialhaving a second Shore D hardness at least 10 points greater than thefirst hardness.

In one embodiment of the above, the polymer comprises ionomericcopolymers and terpolymers, ionomer precursors, thermoplastics,thermoplastic elastomers, polybutadiene rubber, balata, graftedmetallocene-catalyzed polymers, non-grafted metallocene-catalyzedpolymers, single-site polymers, high-crystalline acid polymers, cationicionomers, and mixtures thereof.

In another embodiment of the above, the organic acid is selected fromthe group consisting of aliphatic organic acids, aromatic organic acids,saturated mono-functional organic acids, unsaturated mono-functionalorganic acids, and multi-unsaturated mono-functional organic acids.Preferably, the salt of organic acids comprise the salts of barium,lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium,strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver,aluminum, tin, calcium, stearic, bebenic, erucic, oleic, linoelic,dimerized derivatives, and mixtures thereof.

In another embodiment of the above, the core further comprises a secondpolymer component in an amount sufficient to reduce the core compressionto less than or equal to about 70. Further, preferably the secondpolymer component has a Shore D hardness of about 40 or greater. It isalso preferred that the second polymer component comprises ionomericcopolymers and terpolymers, ionomer precursors, thermoplastics,thermoplastic elastomers, polybutadiene rubber, balata, graftedmetallocene-catalyzed polymers, non-grafted metallocene-catalyzedpolymers, single-site polymers, high-crystalline acid polymers, cationicionomers, and mixtures thereof.

In one embodiment of the above, the organic acid or salt thereof ispresent in an amount sufficient to neutralize the polymer by at leastabout 90%. In a preferred embodiment, the organic acid or salt thereofis present in an amount sufficient to neutralize the polymer by at leastabout 100%. Further, at least one of the polymer or second polymercomponent is partially neutralized by a metal cation.

In another embodiment, the core has a diameter of about 1.58 inches orgreater. The cover may be comprised of a castable reactive liquidmaterial or the cover is cast or reaction injection molded over thecore. Preferably, the cover is comprised of a polyurethane.

The present invention is also directed to a golf ball comprising a corecomprising a center and an outer layer, the center being comprised of athermoset rubber and the outer layer being comprised of polymerneutralized with an organic acid or a salt thereof, the organic acid orsalt thereof being present in an amount greater than about 10 weightpercent such that the polymer is fully neutralized, wherein the outerlayer has a first Shore D hardness and the core has a compression ofless than or equal to about 90 and a diameter of about 1.53 inches orgreater; and a cover being comprised of a castable reactive liquidmaterial having a second Shore D hardness being at least 10 points lessthan the first hardness.

In one embodiment, the outer layer further comprises a softeningcopolymer in sufficient weight percentage to reduce the core compressionto less than or equal to about 70. In another embodiment, the core has adiameter of about 1.58 inches or greater. Preferably, the cover iscomprised of a castable reactive liquid material. The cover may also becast or reaction injection molded over the core. It is preferred thatthe cover is comprised of a cast polyurethane. In another embodiment,the golf ball further comprises an intermediate layer being comprised ofan ionomer having a Shore D hardness that is at least 10 greater thanthe first Shore D hardness.

In an alternative embodiment, the core is surface treated by plasmatreatment, corona discharge, chemical treatment or mechanically treated.

The present invention is also directed to a golf ball comprising a corecomprised of a thermoset rubber having a diameter of about 0.5 to 1.55inches; a cover disposed over the core having a shore D hardness ofabout 55 or less; and an intermediate layer being comprised of a polymerneutralized by an organic acid or a salt thereof, the an organic acid ora salt thereof being present in an amount sufficient to neutralize thepolymer by at least about 100%.

Preferably, the cover is comprised or a polyurethane. In one embodiment,the intermediate layer has a Shore D hardness of at least about 62. Inanother embodiment, the cover has a thickness of about 0.04 or less. Instill another embodiment, the core has a compression of about 70 or lessand a diameter of at least 1.4 inches.

The present invention is also directed to a golf ball comprising acenter comprised of a liquid, the center having a diameter of about 1.0inches or less; an intermediate layer being comprised of a polymerneutralized with an organic acid or a salt thereof, the an organic acidor a salt thereof being present in an amount greater than about 10weight percent such that the polymer is saturated, the intermediatelayer being disposed about the center to form a core; and a coverdisposed over the core.

Preferably, the cover is comprised of a polyurethane. Additionally, thecore is further comprised of an outer layer comprised of a thermosetrubber disposed between the intermediate layer and the cover. In anotherembodiment, the outer layer has a hardness that is at least 5 pointsless than a hardness of the intermediate layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is one embodiment of a golf ball of the present invention;

FIG. 2 is a second embodiment of a golf ball of the present invention;

FIG. 3 is a side view of a golf ball according to the present invention;

FIG. 4 is a cross-sectional view along the line 2—2 of FIG. 3 of thegolf ball according to the present invention;

FIG. 5 is a side view of an inner core of the golf ball shown in FIG. 4;

FIG. 6 is a plan view along the arrow 4 of FIG. 5 of the inner coreaccording to the present invention;

FIGS. 7-12 are cross-sectional views of other embodiments of golf ballsaccording to the present invention;

FIG. 13 is a perspective view of another embodiment of the inner coreaccording to the present invention;

FIG. 14 is a side view of another embodiment of the inner core accordingto the present invention; and

FIG. 15 is a side view of another embodiment of the inner core accordingto the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to highly-neutralized polymers andblends thereof (“HNP”) for the use in golf equipment, preferably in ballcores, intermediate layers, and/or covers. The acid moieties of theHNP's, typically ethylene-based ionomers, are preferably neutralizedgreater than about 70%, more preferably greater than about 90%, and mostpreferably at least about 100%. The HNP's can be also be blended with asecond polymer component, which, if containing an acid group, may beneutralized in a conventional manner, by the organic fatty acids of thepresent invention, or both. The second polymer component, which may bepartially or fully neutralized, preferably comprises ionomericcopolymers and terpolymers, ionomer precursors, thermoplastics,polyamides, polycarbonates, polyesters, polyurethanes, polyureas,thermoplastic elastomers, polybutadiene rubber, balata,metallocene-catalyzed polymers (grafted and non-grafted), single-sitepolymers, high-crystalline acid polymers, cationic ionomers, and thelike. HNP polymers typically have a material hardness of between about20 and about 80 Shore D, and a flexural modulus of between about 3,000psi and about 200,000 psi.

In one embodiment of the present invention the HNP's are ionomers and/ortheir acid precursors that are preferably neutralized, either filly orpartially, with organic acid copolymers or the salts thereof. The acidcopolymers are preferably α-olefin, such as ethylene, C₃₋₈α,β-ethylenically unsaturated carboxylic acid, such as acrylic andmethacrylic acid, copolymers. They may optionally contain a softeningmonomer, such as alkyl acrylate and alkyl methacrylate, wherein thealkyl groups have from 1 to 8 carbon atoms.

The acid copolymers can be described as E/X/Y copolymers where E isethylene, X is an α,β-ethylenically unsaturated carboxylic acid, and Yis a softening comonomer. In a preferred embodiment, X is acrylic ormethacrylic acid and Y is a C₁₋₈ alkyl acrylate or methacrylate ester. Xis preferably present in an amount from about 1 to about 35 weightpercent of the polymer, more preferably from about 5 to about 30 weightpercent of the polymer, and most preferably from about 10 to about 20weight percent of the polymer. Y is preferably present in an amount fromabout 0 to about 50 weight percent of the polymer, more preferably fromabout 5 to about 25 weight percent of the polymer, and most preferablyfrom about 10 to about 20 weight percent of the polymer.

Specific acid-containing ethylene copolymers include, but are notlimited to, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate. Preferred acid-containingethylene copolymers include, ethylene/methacrylic acid/n-butyl acrylate,ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/acrylic acid/ethyl acrylate, ethylene/methacrylicacid/ethyl acrylate, and ethylene/acrylic acid/methyl acrylatecopolymers. The most preferred acid-containing ethylene copolymers are,ethylene/(meth) acrylic acid/n-butyl, acrylate, ethylene/(meth)acrylicacid/ethyl acrylate, and ethylene/(meth) acrylic acid/methyl acrylatecopolymers.

Ionomers are typically neutralized with a metal cation, such as Li, Na,Mg, or Zn. It has been found that by adding sufficient organic acid orsalt of organic acid, along with a suitable base, to the acid copolymeror ionomer, however, the ionomer can be neutralized, without losingprocessability, to a level much greater than for a metal cation.Preferably, the acid moieties are neutralized greater than about 80%,preferably from 90-100%, most preferably 100% without losingprocessability. This accomplished by melt-blending an ethyleneα,β-ethylenically unsaturated carboxylic acid copolymer, for example,with an organic acid or a salt of organic acid, and adding a sufficientamount of a cation source to increase the level of neutralization of allthe acid moieties (including those in the acid copolymer and in theorganic acid) to greater than 90%, (preferably greater than 100%).

The organic acids of the present invention are aliphatic,mono-functional (saturated, unsaturated, or multi-unsaturated) organicacids. Salts of these organic acids may also be employed. The salts oforganic acids of the present invention include the salts of barium,lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium,strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver,aluminum, tin, or calcium, salts of fatty acids, particularly stearic,bebenic, erucic, oleic, linoelic or dimerized derivatives thereof. It ispreferred that the organic acids and salts of the present invention berelatively non-migratory (they do not bloom to the surface of thepolymer under ambient temperatures) and non-volatile (they do notvolatilize at temperatures required for melt-blending).

The ionomers of the invention may also be partially neutralized withmetal cations. The acid moiety in the acid copolymer is neutralizedabout 1 to about 100%, preferably at least about 40 to about 100%, andmore preferably at least about 90 to about 100%, to form an ionomer by acation such as lithium, sodium, potassium, magnesium, calcium, barium,lead, tin, zinc, aluminum, or a mixture thereof.

The acid copolymers of the present invention are prepared from ‘direct’acid copolymers, copolymers polymerized by adding all monomerssimultaneously, or by grafting of at least one acid-containing monomeronto an existing polymer.

Thermoplastic polymer components, such as copolyetheresters,copolyesteresters, copolyetheramides, elastomeric polyolefins, styrenediene block copolymers and their hydrogenated derivatives,copolyesteramides, thermoplastic polyurethanes, such ascopolyetherurethanes, copolyesterurethanes, copolyureaurethanes,epoxy-based polyurethanes, polycaprolactone-based polyurethanes,polyureas, and polycarbonate-based polyurethanes fillers, and otheringredients, if included, can be blended in either before, during, orafter the acid moieties are neutralized, thermoplastic polyurethanes.

The copolyetheresters are comprised of a multiplicity of recurring longchain units and short chain units joined head-to-tail through esterlinkages, the long chain units being represented by the formula:

and the short chain units being represented by the formula:

where G is a divalent radical remaining after the removal of terminalhydroxyl groups from a poly (alkylene oxide) glycol having a molecularweight of about 400-8000 and a carbon to oxygen ratio of about 2.0-4.3;R is a divalent radical remaining after removal of hydroxyl groups froma diol having a molecular weight less than about 250; provided saidshort chain ester units amount to about 15-95 percent by weight of saidcopolyetherester. The preferred copolyetherester polymers are thosewhere the polyether segment is obtained by polymerization oftetrahydrofuran and the polyester segment is obtained by polymerizationof tetramethylene glycol and phthalic acid. For purposes of theinvention, the molar ether:ester ratio can vary from 90:10 to 10:80;preferably 80:20 to 60:40; and the Shore D hardness is less than 70;preferably less than about 40.

The copolyetheramides are comprised of a linear and regular chain ofrigid polyamide segments and flexible polyether segments, as representedby the general formula:

wherein PA is a linear saturated aliphatic polyamide sequence formedfrom a lactam or amino acid having a hydrocarbon chain containing 4 to14 carbon atoms or from an aliphatic C₆-C₈ diamine, in the presence of achain-limiting aliphatic carboxylic diacid having 4-20 carbon atoms;said polyamide having an average molecular weight between 300 and15,000; and PB is a polyoxyalkylene sequence formed from linear orbranched aliphatic polyoxyalkylene glycols, mixtures thereof orcopolyethers derived therefrom, said polyoxyalkylene glycols having amolecular weight of less than or equal to 6000; and n indicates asufficient number of repeating units so that said polyetheramidecopolymer has an intrinsic viscosity of from about 0.6 to about 2.05.The preparation of these polyetheramides comprises the step of reactinga dicarboxylic polyamide, the COOH groups of which are located at thechain ends, with a polyoxyalkylene glycol hydroxylated at the chainends, in the presence of a catalyst such as a tetra-alkyl ortho titanatehaving the general formula Ti(OR)_(x) wherein R is a linear branchedaliphatic hydrocarbon radical having 1 to 24 carbon atoms. Again, themore polyether units incorporated into the copolyetheramide, the softerthe polymer. The ether:amide ratios are as described above for theether:ester ratios, as is the Shore D hardness.

The elastomeric polyolefins are polymers composed of ethylene and higherprimary olefins such as propylene, hexene, octene, and optionally1,4-hexadiene and or ethylidene norbornene or norbomadiene. Theelastomeric polyolefins can be optionally functionalized with maleicanhydride, epoxy, hydroxy, amine, carboxylic acid, sulfonic acid, orthiol groups.

Thermoplastic polyurethanes are linear or slightly chain branchedpolymers consisting of hard blocks and soft elastomeric blocks. They areproduced by reacting soft hydroxy terminated elastomeric polyethers orpolyesters with diisocyanates, such as methylene diisocyanate (“MDI”),p-phenylene diisocyanate (“PPDI”), or toluene diisocyanate (“TDI”).These polymers can be chain extended with glycols, secondary diamines,diacids, or amino alcohols. The reaction products of the isocyanates andthe alcohols are called urethanes and these blocks are relatively hardand high melting. These hard high melting blocks are responsible for thethermoplastic nature of the polyurethanes.

Block styrene diene copolymers and their hydrogenated derivatives arecomposed of polystyrene units and polydiene units. They may also befunctionalized with moieties such as OH, NH₂, epoxy, COOH, and anhydridegroups. The polydiene units are derived from polybutadiene, polyisopreneunits or copolymers of these two. In the case of the copolymer it ispossible to hydrogenate the polyolefin to give a saturated rubberybackbone segments. These materials are usually referred to as SBS, SIS,or SEBS thermoplastic elastomers and they can also be functionalizedwith maleic anhydride.

Grafted metallocene-catalyzed polymers are also useful for blending withthe HNP's of the present invention. The grafted metallocene-catalyzedpolymers, while conventionally neutralized with metal cations, may alsobe neutralized, either partially for fully, with organic acids or saltsthereof and an appropriate base. Grafted metallocene-catalyzed polymersuseful, such as those disclosed in U.S. Pat. Nos. 5,703,166; 5,824,746;5,981,658; and 6,025,442, which are incorporated herein by reference, inthe golf balls of the invention are available in experimental quantitiesfrom DuPont under the tradenames SURLYN® NMO 525D, SURLYN® NMO 524D, andSURLYN® NMO 499D, all formerly known as the FUSABOND® family ofpolymers, or may be obtained by subjecting a non-graftedmetallocene-catalyzed polymer to a post-polymerization reaction toprovide a grafted metallocene-catalyzed polymer with the desired pendantgroup or groups. Examples of metallocene-catalyzed polymers to whichfunctional groups may be grafted for use in the invention include, butare not limited to, homopolymers of ethylene and copolymers of ethyleneand a second olefin, preferably, propylene, butene, pentene, hexene,heptene, octene, and norbornene. Generally, the invention includes golfballs having at least one layer comprising at least one graftedmetallocene-catalyzed polymer or polymer blend, where the graftedmetallocene-catalyzed polymer is produced by grafting a functional grouponto a metallocene-catalyzed polymer having the formula:

wherein R₁ is hydrogen, branched or straight chain alkyl such as methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl, carbocyclic, oraromatic; R₂ is hydrogen, lower alkyl including C₁-C₅; carbocyclic, oraromatic; R₃ is hydrogen, lower alkyl including C₁-C₅, carbocyclic, oraromatic; R₄ is selected from the group consisting of H, C_(n)H_(2n+1),where n=1 to 18, and phenyl, in which from 0 to 5 H within R₄ can bereplaced by substituents COOH, SO₃H, NH₂, F, Cl, Br, I, OH, SH,silicone, lower alkyl esters and lower alkyl ethers, with the provisothat R₃ and R₄ can be combined to form a bicyclic ring; R₅ is hydrogen,lower alkyl including C₁-C₅, carbocyclic, or aromatic; R₆ is hydrogen,lower alkyl including C₁-C₅, carbocyclic, or aromatic; and wherein x, yand z are the relative percentages of each co-monomer. X can range fromabout 1 to 99 percent or more preferably from about 10 to about 70percent and most preferred, from about 10 to 50 percent. Y can be from99 to 1 percent, preferably, from 90 to 30 percent, or most preferably,90 to 50 percent. Z can range from about 0 to about 49 percent. One ofordinary skill in the art would understand that if an acid moiety ispresent as a ligand in the above polymer that it may be neutralized upto 100% with an organic fatty acid as described above.

Metallocene-catalyzed copolymers or terpolymers can be random or blockand may be isotactic, syndiotactic, or atactic. The pendant groupscreating the isotactic, syndiotactic, or atactic polymers are chosen todetermine the interactions between the different polymer chains makingup the resin to control the final properties of the resins used in golfball covers, centers, or intermediate layers. As will be clear to thoseskilled in the art, grafted metallocene-catalyzed polymers useful in theinvention that are formed from metallocene-catalyzed random or blockcopolymers or terpolymers will also be random or block copolymers orterpolymers, and will have the same tacticity of themetallocene-catalyzed polymer backbone.

As used herein, the term “phrase branched or straight chain alkyl” meansany substituted or unsubstituted acyclic carbon-containing compounds.Examples of alkyl groups include lower alkyl, for example, methyl,ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or t-butyl; upper alkyl,for example, octyl, nonyl, decyl, and the like; and lower alkylene, forexample, ethylene, propylene, butylene, pentene, hexene, octene,norbornene, nonene, decene, and the like.

In addition, such alkyl groups may also contain various substituents inwhich one or more hydrogen atoms has been replaced by a functionalgroup. Functional groups include, but are not limited to hydroxyl,amino, carboxyl, sulfonic amide, ester, ether, phosphates, thiol, nitro,silane and halogen (fluorine, chlorine, bromine and iodine), to mentionbut a few.

As used herein, the term “substituted and unsubstituted carbocyclic”means cyclic carbon-containing compounds, including, but not limited tocyclopentyl, cyclohexyl, cycloheptyl, and the like. Such cyclic groupsmay also contain various substituents in which one or more hydrogenatoms has been replaced by a functional group. Such functional groupsinclude those described above, and lower alkyl groups having from 1-28carbon atoms. The cyclic groups of the invention may further comprise aheteroatom.

As mentioned above, R₁ and R₂ can also represent any combination ofalkyl, carbocyclic or aryl groups, for example, 1-cyclohexylpropyl,benzyl cyclohexylmethyl, 2-cyclohexylpropyl, 2,2-methylcyclohexylpropyl,2,2-methylphenylpropyl, and 2,2-methylphenylbutyl.

Non-grafted metallocene-catalyzed polymers useful in the presentinvention are commercially available under the trade name AFFINITY®polyolefin plastomers and ENGAGE® polyolefin elastomers commerciallyavailable from Dow Chemical Company and DuPont-Dow. Other commerciallyavailable metallocene-catalyzed polymers can be used, such as EXACT®,commercially available from Exxon and INSIGHT®, commercially availablefrom Dow. The EXACT® and INSIGHT® line of polymers also have novelrheological behavior in addition to their other properties as a resultof using a metallocene catalyst technology. Metallocene-catalyzedpolymers are also readily available from Sentinel Products Corporationof Hyannis, Mass., as foamed sheets for compression molding.

Monomers useful in the present invention include, but are not limitedto, olefinic monomers having, as a functional group, sulfonic acid,sulfonic acid derivatives, such as chlorosulfonic acid, vinyl ethers,vinyl esters, primary, secondary, and tertiary amines, mono-carboxylicacids, dicarboxylic acids, partially or fully ester-derivatizedmono-carboxylic and dicarboxylic acids, anhydrides of dicarboxylicacids, and cyclic imides of dicarboxylic acids.

In addition, metallocene-catalyzed polymers may also be functionalizedby sulfonation, carboxylation, or the addition of an amine or hydroxygroup. Metallocene-catalyzed polymers functionalized by sulfonation,carboxylation, or the addition of a hydroxy group may be converted toanionic ionomers by treatment with a base. Similarly,metallocene-catalyzed polymers functionalized by the addition of anamine may be converted to cationic ionomers by treatment with an alkylhalide, acid, or acid derivative.

The most preferred monomer is maleic anhydride, which, once attached tothe metallocene-catalyzed polymer by the post-polymerization reaction,may be further subjected to a reaction to form a graftedmetallocene-catalyzed polymer containing other pendant or functionalgroups. For example, reaction with water will convert the anhydride to adicarboxylic acid; reaction with ammonia, alkyl, or aromatic amine formsan amide; reaction with an alcohol results in the formation of an ester;and reaction with base results in the formation of an anionic ionomer.

The HNP's of the present invention may also be blended with single-siteand metallocene catalysts and polymers formed therefrom. As used herein,the term “single-site catalyst,” such as those disclosed in U.S. Pat.No. 6,150,462 which is incorporated herein by reference, refers to acatalyst that contains an ancillary ligand that influences the stearicand electronic characteristics of the polymerizing site in a manner thatprevents formation of secondary polymerizing species. The term“metallocene catalyst” refers to a single-site catalyst wherein theancillary ligands are comprising substituted or unsubstitutedcyclopentadienyl groups, and the term “non-metallocene catalyst” refersto a single-site catalyst other than a metallocene catalyst.

Non-metallocene single-site catalysts include, but are not limited to,the Brookhart catalyst, which has the following structure:

wherein M is nickel or palladium; R and R′ are independently hydrogen,hydrocarbyl, or substituted hydrocarbyl; Ar is (CF₃)₂C₆H₃, and X isalkyl, methyl, hydride, or halide; the McConville catalyst, which hasthe structure:

wherein M is titanium or zirconium. Iron (II) and cobalt (II) complexeswith 2,6-bis(imino) pyridyl ligands, which have the structure:

where M is the metal, and R is hydrogen, alkyl, or hydrocarbyl. Titaniumor zirconium complexes with pyrroles as ligands also serve assingle-site catalysts. These complexes have the structure:

where M is the metal atom; m and n are independently 1 to 4, andindicate the number of substituent groups attached to the aromaticrings; R_(m) and R_(n) are independently hydrogen or alkyl; and X ishalide or alkyl. Other examples include diimide complexes of nickel andpalladium, which have the structure:

where Ar is aromatic, M is the metal, and X is halide or alkyl.Boratabenzene complexes of the Group IV or V metals also function assingle-site catalysts. These complexes have the structure:

where B is boron and M is the metal atom.

As used herein, the term “single-site catalyzed polymer” refers to anypolymer, copolymer, or terpolymer, and, in particular, any polyolefinpolymerized using a single-site catalyst. The term “non-metallocenesingle-site catalyzed polymer” refers to any polymer, copolymer, orterpolymer, and, in particular, any polyolefin polymerized using asingle-site catalyst other than a metallocene-catalyst. The catalystsdiscussed above are examples of non-metallocene single-site catalysts.The term “metallocene catalyzed polymer” refers to any polymer,copolymer, or terpolymer, and, in particular, any polyolefin,polymerized using a metallocene catalyst.

As used herein, the term “single-site catalyzed polymer blend” refers toany blend of a single-site catalyzed polymer and any other type ofpolymer, preferably an ionomer, as well as any blend of a single-sitecatalyzed polymer with another single-site catalyzed polymer, including,but not limited to, a metallocene-catalyzed polymer.

The terms “grafted single-site catalyzed polymer” and “graftedsingle-site catalyzed polymer blend” refer to any single-site catalyzedpolymer or single-site catalyzed polymer blend in which the single-sitecatalyzed polymer has been subjected to a post-polymerization reactionto graft at least one functional group onto the single-site catalyzedpolymer. A “post-polymerization reaction” is any reaction that occursafter the formation of the polymer by a polymerization reaction.

The single-site catalyzed polymer, which may be grafted, may also beblended with polymers, such as non-grafted single-site catalyzedpolymers, grafted single-site catalyzed polymers, ionomers, andthermoplastic elastomers. Preferably, the single-site catalyzed polymeris blended with at least one ionomer of the preset invention.

Grafted single-site catalyzed polymers useful in the golf balls of theinvention may be obtained by subjecting a non-grafted single-sitecatalyzed polymer to a post-polymerization reaction to provide a graftedsingle-site catalyzed polymer with the desired pendant group or groups.Examples of single-site catalyzed polymers to which functional groupsmay be grafted for use in the invention include, but are not limited to,homopolymers of ethylene and propylene and copolymers of ethylene and asecond olefin, preferably, propylene, butene, pentene, hexene, heptene,octene, and norbornene. Monomers useful in the present inventioninclude, but are not limited to olefinic monomers having as a functionalgroup sulfonic acid, sulfonic acid derivatives, such as chlorosulfonicacid, vinyl ethers, vinyl esters, primary, secondary, and tertiaryamines, epoxies, isocyanates, mono-carboxylic acids, dicarboxylic acids,partially or fully ester derivatized mono-carboxylic and dicarboxylicacids, anhydrides of dicarboxylic acids, and cyclic imides ofdicarboxylic acids. Generally, this embodiment of the invention includesgolf balls having at least one layer comprising at least one graftedsingle-site catalyzed polymer or polymer blend, where the graftedsingle-site catalyzed polymer is produced by grafting a functional grouponto a single-site catalyzed polymer having the formula:

where R₁ is hydrogen, branched or straight chain alkyl such as methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl, carbocyclic,aromatic or heterocyclic; R₂, R₃, R₅, and R₆ are hydrogen, lower alkylincluding C₁-C₅, carbocyclic, aromatic or heterocyclic; R₄ is H,C_(n)H_(2n+1), where n=1 to 18, and phenyl, in which from 0 to 5 Hwithin R₄ can be replaced by substituents such as COOH, SO₃H, NH₂, F,Cl, Br, I, OH, SH, epoxy, isocyanate, silicone, lower alkyl esters andlower alkyl ethers; also, R₃ and R₄ can be combined to form a bicyclicring; and x, y and z are the relative percentages of each co-monomer. Xcan range from about 1 to about 100 percent or more preferably from 1 to70 percent and most preferred, from about 1 to about 50 percent. Y canbe from about 99 to about 0 percent, preferably, from about 9 to about30 percent, or most preferably, about 9 to about 50 percent. Z can rangefrom about 0 to about 50 percent. One of ordinary skill in the art wouldalso understand that if an acid group is selected as a ligand in theabove structure that it too could be neutralized with the organic fattyacids described above.

The HNP's of the present invention may also be blended with highcrystalline acid copolymers and their ionomer derivatives (which may beneutralized with conventional metal cations or the organic fatty acidsand salts thereof) or a blend of a high crystalline acid copolymer andits ionomer derivatives and at least one additional material, preferablyan acid copolymer and its ionomer derivatives. As used herein, the term“high crystalline acid copolymer” is defined as a “product-by-process”in which an acid copolymer or its ionomer derivatives formed from aethylene/carboxylic acid copolymer comprising about 5 to about 35percent by weight acrylic or methacrylic acid, wherein the copolymer ispolymerized at a temperature of about 130° C. to 200° C., at pressuresgreater than about 20,000 psi preferably greater than about 25,000 psi,more pref. from about 25,000 psi to about 50,000 psi, wherein up toabout 70 percent, preferably 100 percent, of the acid groups areneutralized with a metal ion, organic fatty acids and salts thereof, ora mixture thereof. The copolymer can have a melt index (“MI”) of fromabout 20 to about 300 g/10 min, preferably about 20 to about 200 g/10min, and upon neutralization of the copolymer, the resulting acidcopolymer and its ionomer derivatives should have an MI of from about0.1 to about 30.0 g/10 min.

Suitable high crystalline acid copolymer and its ionomer derivativescompositions and methods for making them are disclosed in U.S. Pat. No.5,580,927, the disclosure of which is hereby incorporated by referencein its entirety.

The high crystalline acid copolymer or its ionomer derivatives employedin the present invention are preferably formed from a copolymercontaining about 5 to about 35 percent, more preferably from about 9 toabout 18, most preferably about 10 to about 13 percent, by weight ofacrylic acid, wherein up to about 75 percent, most preferably about 60percent, of the acid groups are neutralized with an organic fatty acid,salt thereof, or a metal ion, such as sodium, lithium, magnesium, orzinc ion.

Generally speaking, high crystalline acid copolymer and its ionomerderivatives are formed by polymerization of their base copolymers atlower temperatures, but at equivalent pressures to those used forforming a conventional acid copolymer and its ionomer derivatives.Conventional acid copolymers are typically polymerized at apolymerization temperature of from at least about 200° C. to about 270°C., preferably about 220° C., and at pressures of from about 23,000 toabout 30,000 psi. In comparison, the high crystalline acid copolymer andits ionomer derivatives employed in the present invention are producedfrom acid copolymers that are polymerized at a polymerizationtemperature of less than 200° C., and preferably from about 130° C. toabout 200° C., and at pressures from about 20,000 to about 50,000 psi.

The HNP's of the present invention may also be blended with cationicionomers, such as those disclosed in U.S. Pat. No. 6,193,619 which isincorporated herein by reference. In particular, cationic ionomers havea structure according to the formula:

wherein R₁-R₉ are organic moieties of linear or branched chain alkyl,carbocyclic, or aryl; and Z is the negatively charged conjugate ionproduced following alkylation and/or quaternization. The cationicpolymers may also be quarternized up to 100% by the organic fatty acidsdescribed above.

In addition, such alkyl group may also contain various substituents inwhich one or more hydrogen atoms has been replaced by a functionalgroup. Functional groups include but are not limited to hydroxyl, amino,carboxyl, amide, ester, ether, sulfonic, siloxane, siloxyl, silanes,sulfonyl, and halogen.

As used herein, substituted and unsubstituted carbocyclic groups of upto about 20 carbon atoms means cyclic carbon-containing compounds,including but not limited to cyclopentyl, cyclohexyl, cycloheptyl, andthe like. Such cyclic groups may also contain various substituents inwhich one or more hydrogen atoms has been replaced by a functionalgroup. Such functional groups include those described above, and loweralkyl groups as described above. The cyclic groups of the invention mayfurther comprise a heteroatom.

The HNP's of the present invention may also be blended with polyurethaneand polyurea ionomers which include anionic moieties or groups, such asthose disclosed in U.S. Pat. No. 6,207,784 which is incorporated hereinby reference. Typically, such groups are incorporated onto thediisocyanate or diisocyanate component of the polyurethane or polyureaionomers. The anionic group can also be attached to the polyol or aminecomponent of the polyurethane or polyurea, respectively. Preferably, theanionic group is based on a sulfonic, carboxylic or phosphoric acidgroup. Also, more than one type of anionic group can be incorporatedinto the polyurethane or polyurea. Examples of anionic polyurethaneionomers with anionic groups attached to the diisocyanate moiety canhave a chemical structure according to the following formula:

where A=R—Z⁻M^(+x); R is a straight chain or branched aliphatic group, asubstituted straight chain or branched aliphatic group, or an aromaticor substituted aromatic group; Z=SO₃ ⁻, CO₂ ⁻ or HPO₃ ⁻; M is a groupIA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIBmetal; x=1 to 5; B is a straight chain or branched aliphatic group, asubstituted straight chain or branched aliphatic group, or an aromaticor substituted aromatic group; and n=1 to 100. Preferably, M^(+x) is oneof the following: Li⁺, Na⁺, K⁺, Mg⁺², Zn⁺², Ca⁺², Mn⁺², Al⁺³, Ti^(+x),Zr^(+x), W^(+x) or Hf^(+x).

Exemplary anionic polyurethane ionomers with anionic groups attached tothe polyol component of the polyurethane are characterized by the abovechemical structure where A is a straight chain or branched aliphaticgroup, a substituted straight chain or branched aliphatic group, or anaromatic or substituted aromatic group; B=R—Z⁻M^(+x); R is a straightchain or branched aliphatic group, a substituted straight chain orbranched aliphatic group, or an aromatic or substituted aromatic group;Z=SO₃ ⁻, CO₂ ⁻ or HPO₃ ⁻; M is a group IA, IB, IIA, IIB, IIIA, IIIB,IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIB metal; x=1 to 5; and n=1 to100. Preferably, M^(+x) is one of the following: Li⁺, Na⁺, K⁺, Mg⁺²,Zn⁺², Ca⁺², Mn⁺², Al⁺³, Ti^(+x), Zr^(+x), W^(+x) or Hf^(+x).

Examples of suitable anionic polyurea ionomers with anionic groupsattached to the diisocyanate component have a chemical structureaccording to the following chemical structure:

where A=R—Z⁻M^(+x); R is a straight chain or branched aliphatic group, asubstituted straight chain or branched aliphatic group, or an aromaticor substituted aromatic group; Z=SO₃ ⁻, CO₂ ⁻ or HPO₃ ⁻; M is a groupIA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIIB or VIIIBmetal; x=1 to 5; and B is a straight chain or branched aliphatic group,a substituted straight chain or branched aliphatic group, or an aromaticor substituted aromatic group. Preferably, M^(+x) is one of thefollowing: Li⁺, Na⁺, K⁺, Mg⁺², Zn⁺², Ca⁺², Mn⁺², Al⁺³, Ti^(+x), Zr^(+x),W^(+x), or Hf^(+x).

Suitable anionic polyurea ionomers with anionic groups attached to theamine component of the polyurea are characterized by the above chemicalstructure where A is a straight chain or branched aliphatic group, asubstituted straight chain or branched aliphatic group, or an aromaticor substituted aromatic group; B=R—Z⁻M^(+x); R is a straight chain orbranched aliphatic group, a substituted straight chain or branchedaliphatic group, or an aromatic or substituted aromatic group; Z=SO₃ ⁻,CO₂ ⁻ or HPO₃ ⁻; M is a group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB,VA, VB, VIA, VIB, VIIB or VIIIB metal; and x=1 to 5. Preferably, M^(+x)is one of the following: Li⁺, Na⁺, K⁺, Mg⁺², Zn⁺², Ca⁺², Mn⁺², Al⁺³,Ti^(+x), Zr^(+x), W^(+x), or Hf^(+x). The anionic polyurethane andpolyurea ionomers may also be neutralized up to 100% by the organicfatty acids described above.

The anionic polymers useful in the present invention, such as thosedisclosed in U.S. Pat. No. 6,221,960 which is incorporated herein byreference, include any homopolymer, copolymer or terpolymer havingneutralizable hydroxyl and/or dealkylable ether groups, and in which atleast a portion of the neutralizable or dealkylable groups areneutralized or dealkylated with a metal ion.

As used herein “neutralizable” or “dealkylable” groups refer to ahydroxyl or ether group pendent from the polymer chain and capable ofbeing neutralized or dealkylated by a metal ion, preferably a metal ionbase. These neutralized polymers have improved properties critical togolf ball performance, such as resiliency, impact strength and toughnessand abrasion resistance. Suitable metal bases are ionic compoundscomprising a metal cation and a basic anion. Examples of such basesinclude hydroxides, carbonates, acetates, oxides, sulfides, and thelike.

The particular base to be used depends upon the nature of the hydroxylor ether compound to be neutralized or dealkylated, and is readilydetermined by one skilled in the art. Preferred anionic bases includehydroxides, carbonates, oxides and acetates.

The metal ion can be any metal ion which forms an ionic compound withthe anionic base. The metal is not particularly limited, and includesalkali metals, preferably lithium, sodium or potassium; alkaline earthmetals, preferably magnesium or calcium; transition metals, preferablytitanium, zirconium, or zinc; and Group III and IV metals. The metal ioncan have a +1 to +5 charge. Most preferably, the metal is lithium,sodium, potassium, zinc, magnesium, titanium, tungsten, or calcium, andthe base is hydroxide, carbonate or acetate.

The anionic polymers useful in the present invention include those whichcontain neutralizable hydroxyl and/or dealkylable ether groups.Exemplary polymers include ethylene vinyl alcohol copolymers, polyvinylalcohol, polyvinyl acetate, poly(p-hydroxymethylene styrene), andp-methoxy styrene, to name but a few. It will be apparent to one skilledin the art that many such polymers exist and thus can be used in thecompositions of the invention. In general, the anionic polymer can bedescribed by the chemical structure:

where R₁ is OH, OC(O)R_(a), O—M^(+V), (CH₂)_(n)R_(b),(CHR_(z))_(n)R_(b), or aryl, wherein n is at least 1, R_(a) is a loweralkyl, M is a metal ion, V is an integer from 1 to 5, R_(b) is OH,OC(O)R_(a), O—M^(+V), and R_(z) is a lower alkyl or aryl, and R₂, R₃ andR₄ are each independently hydrogen, straight-chain or branched-chainlower alkyl. R₂, R₃ and R₄ may also be similarly substituted. Preferablyn is from 1 to 12, more preferably 1 to 4.

The term “substituted,” as used herein, means one or more hydrogen atomshas been replaced by a functional group. Functional groups include, butare not limited to, hydroxyl, amino, carboxyl, sulfonic, amide, ether,ether, phosphates, thiol, nitro, silane, and halogen, as well as manyothers which are quite familiar to those of ordinary skill in this art.

The terms “alkyl” or “lower alkyl,” as used herein, includes a group offrom about 1 to 30 carbon atoms, preferably 1 to 10 carbon atoms.

In the anionic polymers useful in the present invention, at least aportion of the neutralizable or dealkylable groups of R₁ are neutralizedor dealkylated by an organic fatty acid, a salt thereof, a metal base,or a mixture thereof to form the corresponding anionic moiety. Theportion of the neutralizable or dealkylable groups which are neutralizedor dealkylated can be between about 1 to about 100 weight percent,preferably between about 50 to about 100 weight percent, more preferablybefore about 90 to about 100.

Neutralization or dealkylation may be performed by melting the polymerfirst, then adding a metal ion in an extruder. The degree ofneutralization or dealkylation is controlled by varying the amount ofmetal ion added. Any method of neutralization or dealkylation availableto those of ordinary skill in the art may also be suitably employed.

In one embodiment, the anionic polymer is repeating units any one of thethree homopolymer units in the chemical structure above. In a preferredembodiment, R₂, R₃ and R₄ are hydrogen, and R₁ is hydroxyl, i.e., theanionic polymer is a polyvinyl alcohol homopolymer in which a portion ofthe hydroxyl groups have been neutralized with a metal base. In anotherpreferred embodiment, R₂, R₃ and R₄ are hydrogen, R₁ is OC(O)R_(a), andR_(a) is methyl, i.e., the anionic polymer is a polyvinyl acetatehomopolymer in which a portion of the methyl ether groups have beendealkylated with a metal ion.

The anionic polymer can also be a copolymer of two different repeatingunits having different substituents, or a terpolymer of three differentrepeating units described in the above formula. In this embodiment, thepolymer can be a random copolymer, an alternating copolymer, or a blockcopolymer, where the term “copolymer” includes terpolymers.

In another embodiment, the anionic polymer is a copolymer, wherein R₅,R₆, R₇ and R₈ are each independently selected from the group definedabove for R₂. The first unit of the copolymer can comprise from about 1to 99 percent weight percent of the polymer, preferably from about 5 to50 weight percent, and the second unit of the copolymer can comprisefrom about 99 to 1 weight percent, preferably from about 95 to 50 weightpercent. In one preferred embodiment, the anionic polymer is a random,alternating or block copolymer of units (Ia) and (Ib) wherein R₁ ishydroxyl, and each of the remaining R groups is hydrogen, i.e., thepolymer is a copolymer of ethylene and vinyl alcohol. In anotherpreferred embodiment, the anionic polymer is a random, alternating orblock copolymer of units (Ia) and (Ib) wherein R₁ is OC(O)R₅, where R₅is methyl, and each of the remaining R groups is hydrogen, i.e., thepolymer is a copolymer of ethylene and vinyl acetate.

In another embodiment, the anionic polymer is an anionic polymer havingneutralizable hydroxyl and/or dealkylable ether groups of as in theabove chemical structure wherein R₁₋₉ and R_(b) and R_(z) are as definedabove; R₁₀₋₁₁ are each independently selected from the group as definedabove for R₂; and R₁₂ is OH or OC(O)R₁₃, where R₁₃ is a lower alkyl;wherein x, y and z indicate relative weight percent of the differentunits. X can be from about 99 to about 50 weight percent of the polymer,y can be from about 1 to about 50 weight percent of the polymer, and zranges from about 0 to about 50 weight percent of the polymer. At leasta portion of the neutralizable groups R₁ are neutralized. When theamount of z is greater than zero, a portion of the groups R₁₀ can alsobe fully or partially neutralized, as desired.

In particular, the anionic polymers and blends thereof can comprisecompatible blends of anionic polymers and ionomers, such as the ionomersdescribed above, and ethylene acrylic methacrylic acid ionomers, andtheir terpolymers, sold commercially under the trade names SURLYN® andIOTEK® by DuPont and Exxon respectively. The anionic polymer blendsuseful in the golf balls of the invention can also include otherpolymers, such as polyvinylalcohol, copolymers of ethylene and vinylalcohol, poly(ethylethylene), poly(heptylethylene),poly(hexyldecylethylene), poly(isopentylethylene), poly(butyl acrylate),acrylate), poly(2-ethylbutyl acrylate), poly(heptyl acrylate),poly(2-methylbutyl acrylate), poly(3-methylbutyl acrylate),poly(N-octadecylacrylamide), poly(octadecyl methacrylate),poly(butoxyethylene), poly(methoxyethylene), poly(pentyloxyethylene),poly(1,1-dichloroethylene), poly(4-[(2-butoxyethoxy)methyl]styrene),poly[oxy(ethoxymethyl)ethylene], poly(oxyethylethylene),poly(oxytetramethylene), poly(oxytrimethylene), poly(silanes) andpoly(silazanes), polyamides, polycarbonates, polyesters, styrene blockcopolymers, polyetheramides, polyurethanes, main-chain heterocyclicpolymers and poly(furan tetracarboxylic acid diimides), as well as theclasses of polymers to which they belong.

The anionic polymer compositions of the present invention typically havea flexural modulus of from about 500 psi to about 300,000 psi,preferably from about 2000 to about 200,000 psi. The anionic polymercompositions typically have a material hardness of at least about 15Shore A, preferably between about 30 Shore A and 80 Shore D, morepreferably between about 50 Shore A and 60 Shore D. The loss tangent, ordissipation factor, is a ratio of the loss modulus over the dynamicshear storage modulus, and is typically less than about 1, preferablyless than about 0.01, and more preferably less than about 0.001 for theanionic polymer compositions measured at about 23° C. The specificgravity is typically greater than about 0.7, preferably greater thanabout 1, for the anionic polymer compositions. The dynamic shear storagemodulus, or storage modulus, of the anionic polymer compositions atabout 23° C. is typically at least about 10,000 dyn/cm².

The golf balls of the present invention may comprise a variety ofconstructions. Referring to FIG. 1, in one embodiment of the presentinvention, golf ball 10 includes a core 12, an inner cover layer 14surrounding the core 12, and an outer cover layer 16. Preferably, thecore 12 is solid.

In a preferred embodiment, the solid core 12 comprises the HNP's of thepresent invention. In an alternative embodiment, the solid core 12 mayinclude compositions having a base rubber, a crosslinking agent, afiller, and a co-crosslinking or initiator agent, and the inner coverlayer 14 comprises the HNP's of the present invention.

The base rubber typically includes natural or synthetic rubbers. Apreferred base rubber is 1,4-polybutadiene having a cis-structure of atleast 40%. More preferably, the base rubber compriseshigh-Mooney-viscosity rubber. If desired, the polybutadiene can also bemixed with other elastomers known in the art such as natural rubber,polyisoprene rubber and/or styrene-butadiene rubber in order to modifythe properties of the core.

The crosslinking agent includes a metal salt of an unsaturated fattyacid such as a zinc salt or a magnesium salt of an unsaturated fattyacid having 3 to 8 carbon atoms such as acrylic or methacrylic acid.Suitable cross linking agents include metal salt diacrylates,dimethacrylates and monomethacrylates wherein the metal is magnesium,calcium, zinc, aluminum, sodium, lithium or nickel. The crosslinkingagent is present in an amount from about 15 to about 30 parts perhundred of the rubber, preferably in an amount from about 19 to about 25parts per hundred of the rubber and most preferably having about 20 to24 parts crosslinking agent per hundred of rubber. The core compositionsof the present invention may also include at least one organic orinorganic cis-trans catalyst to convert a portion of the cis-isomer ofpolybutadiene to the trans-isomer, as desired.

The initiator agent can be any known polymerization initiator whichdecomposes during the cure cycle. Suitable initiators include peroxidecompounds such as dicumyl peroxide, 1,1-di-(t-butylperoxy)3,3,5-trimethyl cyclohexane, a-a bis-(t-butylperoxy) diisopropylbenzene,2,5-dimethyl-2,5di-(t-butylperoxy) hexane or di-t-butyl peroxide andmixtures thereof.

Fillers, any compound or composition that can be used to vary thedensity and other properties of the core, typically include materialssuch as tungsten, zinc oxide, barium sulfate, silica, calcium carbonate,zinc carbonate, metals, metal oxides and salts, regrind (recycled corematerial typically ground to about 30 mesh particle),high-Mooney-viscosity rubber regrind, and the like.

The golf ball cores of the present invention may also comprise a varietyof constructions. For example, the core may comprise a single layer or aplurality of layers. The core may also comprise a formed of a tensionedelastomeric material. Referring to FIG. 2, in another embodiment of thepresent invention, golf ball 20 comprises a solid center 22 surroundedby at least one additional solid outer core layer 24. The “dual” core 26is surrounded by a “double” cover 28 comprising an inner cover layer 30and an outer cover layer 32.

Preferably, the solid center 22 comprises the HNP's of the presentinvention. In another embodiment, the inner cover layer 28 comprises thehighly-neutralized acid copolymers of the present invention. In analternative embodiment, the outer core layer 24 comprises thehighly-neutralized acid copolymers of the present invention.

At least one of the outer core layers is formed of a resilientrubber-based component comprising a high-Mooney-viscosity rubber, and acrosslinking agent present in an amount from about 20 to about 40 partsper hundred, from about 30 to about 38 parts per hundred, and mostpreferably about 37 parts per hundred. It should be understood that theterm “parts per hundred” is with reference to the rubber by weight.

When the golf ball of the present invention includes an intermediatelayer, such as an outer core layer or an inner cover layer, any or allof these layer(s) may comprise thermoplastic and thermosetting material,but preferably the intermediate layer(s), if present, comprise anysuitable material, such as ionic copolymers of ethylene and anunsaturated monocarboxylic acid which are available under the trademarkSURLYN® of E. I. DuPont de Nemours & Co., of Wilmington, Del., or IOTEK®or ESCOR® of Exxon. These are copolymers or terpolymers of ethylene andmethacrylic acid or acrylic acid partially neutralized with salts ofzinc, sodium, lithium, magnesium, potassium, calcium, manganese, nickelor the like, in which the salts are the reaction product of an olefinhaving from 2 to 8 carbon atoms and an unsaturated monocarboxylic acidhaving 3 to 8 carbon atoms. The carboxylic acid groups of the copolymermay be totally or partially neutralized and might include methacrylic,crotonic, maleic, fumaric or itaconic acid.

This golf ball can likewise include one or more homopolymeric orcopolymeric inner cover materials, such as:

(1) Vinyl resins, such as those formed by the polymerization of vinylchloride, or by the copolymerization of vinyl chloride with vinylacetate, acrylic esters or vinylidene chloride;

(2) Polyolefins, such as polyethylene, polypropylene, polybutylene andcopolymers such as ethylene methylacrylate, ethylene ethylacrylate,ethylene vinyl acetate, ethylene methacrylic or ethylene acrylic acid orpropylene acrylic acid and copolymers and homopolymers produced using asingle-site catalyst or a metallocene catalyst;

(3) Polyurethanes, such as those prepared from polyols and diisocyanatesor polyisocyanates, in particular PPDI-based thermoplasticpolyurethanes, and those disclosed in U.S. Pat. No. 5,334,673;

(4) Polyureas, such as those disclosed in U.S. Pat. No. 5,484,870;

(5) Polyamides, such as poly(hexamethylene adipamide) and othersprepared from diamines and dibasic acids, as well as those from aminoacids such as poly(caprolactam), and blends of polyamides with SURLYN®,polyethylene, ethylene copolymers, ethylene-propylene-non-conjugateddiene terpolymer, and the like;

(6) Acrylic resins and blends of these resins with poly vinyl chloride,elastomers, and the like;

(7) Thermoplastics, such as urethane; olefinic thermoplastic rubbers,such as blends of polyolefins with ethylene-propylene-non-conjugateddiene terpolymer; block copolymers of styrene and butadiene, isoprene orethylene-butylene rubber; or copoly(ether-amide), such as PEBAX®, soldby ELF Atochem of Philadelphia, Pa.;

(8) Polyphenylene oxide resins or blends of polyphenylene oxide withhigh impact polystyrene as sold under the trademark NORYL® by GeneralElectric Company of Pittsfield, Mass.;

(9) Thermoplastic polyesters, such as polyethylene terephthalate,polybutylene terephthalate, polyethylene terephthalate/glycol modified,poly(trimethylene terepthalate), and elastomers sold under thetrademarks HYTREL® by E. I. DuPont de Nemours & Co. of Wilmington, Del.,and LOMOD® by General Electric Company of Pittsfield, Mass.;

(10) Blends and alloys, including polycarbonate with acrylonitrilebutadiene styrene, polybutylene terephthalate, polyethyleneterephthalate, styrene maleic anhydride, polyethylene, elastomers, andthe like, and polyvinyl chloride with acrylonitrile butadiene styrene orethylene vinyl acetate or other elastomers; and

(11) Blends of thermoplastic rubbers with polyethylene, propylene,polyacetal, nylon, polyesters, cellulose esters, and the like.

Preferably, the inner cover includes polymers, such as ethylene,propylene, butene-1 or hexane-1 based homopolymers or copolymersincluding functional monomers, such as acrylic and methacrylic acid andfully or partially neutralized ionomer resins and their blends, methylacrylate, methyl methacrylate homopolymers and copolymers, imidized,amino group containing polymers, polycarbonate, reinforced polyamides,polyphenylene oxide, high impact polystyrene, polyether ketone,polysulfone, poly(phenylene sulfide), acrylonitrile-butadiene,acrylic-styrene-acrylonitrile, poly(ethylene terephthalate),poly(butylene terephthalate), poly(vinyl alcohol),poly(tetrafluoroethylene) and their copolymers including functionalcomonomers, and blends thereof. Suitable cover compositions also includea polyether or polyester thermoplastic urethane, a thermosetpolyurethane, a low modulus ionomer, such as acid-containing ethylenecopolymer ionomers, including E/X/Y terpolymers where E is ethylene, Xis an acrylate or methacrylate-based softening comonomer present inabout 0 to 50 weight percent and Y is acrylic or methacrylic acidpresent in about 5 to 35 weight percent. More preferably, in a low spinrate embodiment designed for maximum distance, the acrylic ormethacrylic acid is present in about 16 to 35 weight percent, making theionomer a high modulus ionomer. In a higher spin embodiment, the innercover layer includes an ionomer where an acid is present in about 10 to15 weight percent and includes a softening comonomer. Additionally,high-density polyethylene (“HDPE”), low-density polyethylene (“LDPE”),LLDPE, and homo- and co-polymers of polyolefin are suitable for avariety of golf ball layers.

In one embodiment, the outer cover preferably includes a polyurethanecomposition comprising the reaction product of at least onepolyisocyanate, polyol, and at least one curing agent. Anypolyisocyanate available to one of ordinary skill in the art is suitablefor use according to the invention. Exemplary polyisocyanates include,but are not limited to, 4,4′-diphenylmethane diisocyanate (“MDI”);polymeric MDI; carbodiimide-modified liquid MDI;4,4′-dicyclohexylmethane diisocyanate (“H₁₂MDI”); p-phenylenediisocyanate (“PPDI”); m-phenylene diisocyanate (“MPDI”); toluenediisocyanate (“TDI”); 3,3′-dimethyl-4,4′-biphenylene diisocyanate(“TODI”); isophoronediisocyanate (“IPDI”); hexamethylene diisocyanate(“HDI”); naphthalene diisocyanate (“NDI”); xylene diisocyanate (“XDI”);p-tetramethylxylene diisocyanate (“p-TMXDI”); m-tetramethylxylenediisocyanate (“m-TMXDI”); ethylene diisocyanate;propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyldiisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”);dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methylcyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of2,4,4-trimethyl-1,6-hexane diisocyanate (“TMDI”); tetracenediisocyanate; napthalene diisocyanate; anthracene diisocyanate;isocyanurate of toluene diisocyanate; uretdione of hexamethylenediisocyanate; and mixtures thereof. Polyisocyanates are known to thoseof ordinary skill in the art as having more than one isocyanate group,e.g., di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably,the polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, andmore preferably, the polyisocyanate includes MDI. It should beunderstood that, as used herein, the term “MDI” includes4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modifiedliquid MDI, and mixtures thereof and, additionally, that thediisocyanate employed may be “low free monomer,” understood by one ofordinary skill in the art to have lower levels of “free” monomerisocyanate groups, typically less than about 0.1% free monomer groups.Examples of “low free monomer” diisocyanates include, but are notlimited to Low Free Monomer MDI, Low Free Monomer TDI, and Low FreeMonomer PPDI.

The at least one polyisocyanate should have less than about 14%unreacted NCO groups. Preferably, the at least one polyisocyanate has nogreater than about 7.5% NCO, and more preferably, less than about 7.0%.

Any polyol available to one of ordinary skill in the art is suitable foruse according to the invention. Exemplary polyols include, but are notlimited to, polyether polyols, hydroxy-terminated polybutadiene(including partially/fully hydrogenated derivatives), polyester polyols,polycaprolactone polyols, and polycarbonate polyols. In one preferredembodiment, the polyol includes polyether polyol. Examples include, butare not limited to, polytetramethylene ether glycol (“PTMEG”),polyethylene propylene glycol, polyoxypropylene glycol, and mixturesthereof. The hydrocarbon chain can have saturated or unsaturated bondsand substituted or unsubstituted aromatic and cyclic groups. Preferably,the polyol of the present invention includes PTMEG.

In another embodiment, polyester polyols are included in thepolyurethane material of the invention. Suitable polyester polyolsinclude, but are not limited to, polyethylene adipate glycol;polybutylene adipate glycol; polyethylene propylene adipate glycol;o-phthalate-1,6-hexanediol; poly(hexamethylene adipate) glycol; andmixtures thereof. The hydrocarbon chain can have saturated orunsaturated bonds, or substituted or unsubstituted aromatic and cyclicgroups.

In another embodiment, polycaprolactone polyols are included in thematerials of the invention. Suitable polycaprolactone polyols include,but are not limited to, 1,6-hexanediol-initiated polycaprolactone,diethylene glycol initiated polycaprolactone, trimethylol propaneinitiated polycaprolactone, neopentyl glycol initiated polycaprolactone,1,4-butanediol-initiated polycaprolactone, and mixtures thereof. Thehydrocarbon chain can have saturated or unsaturated bonds, orsubstituted or unsubstituted aromatic and cyclic groups.

In yet another embodiment, the polycarbonate polyols are included in thepolyurethane material of the invention. Suitable polycarbonates include,but are not limited to, polyphthalate carbonate and poly(hexamethylenecarbonate) glycol. The hydrocarbon chain can have saturated orunsaturated bonds, or substituted or unsubstituted aromatic and cyclicgroups. In one embodiment, the molecular weight of the polyol is fromabout 200 to about 4000.

Polyamine curatives are also suitable for use in the polyurethanecomposition of the invention and have been found to improve cut, shear,and impact resistance of the resultant balls. Preferred polyaminecuratives include, but are not limited to,3,5-dimethylthio-2,4-toluenediamine and isomers thereof;3,5-diethyltoluene-2,4-diamine and isomers thereof, such as3,5-diethyltoluene-2,6-diamine;4,4′-bis-(sec-butylamino)-diphenylmethane;1,4-bis-(sec-butylamino)-benzene, 4,4′-methylene-bis-(2-chloroaniline);4,4′-methylene-bis-(3-chloro-2,6-diethylaniline) (“MCDEA”);polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenylmethane; p,p′-methylene dianiline (“MDA”); m-phenylenediamine (“MPDA”);4,4′-methylene-bis-(2-chloroaniline) (“MOCA”);4,4′-methylene-bis-(2,6-diethylaniline) (“MDEA”);4,4′-methylene-bis-(2,3-dichloroaniline) (“MDCA”);4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane;2,2′,3,3′-tetrachloro diamino diphenylmethane; trimethylene glycoldi-p-aminobenzoate; and mixtures thereof. Preferably, the curing agentof the present invention includes 3,5-dimethylthio-2,4-toluenediamineand isomers thereof, such as ETHACURE 300, commercially available fromAlbermarle Corporation of Baton Rouge, La. Suitable polyamine curatives,which include both primary and secondary amines, preferably havemolecular weights ranging from about 64 to about 2000.

At least one of a diol, triol, tetraol, or hydroxy-terminated curativesmay be added to the aforementioned polyurethane composition. Suitablediol, triol, and tetraol groups include ethylene glycol; diethyleneglycol; polyethylene glycol; propylene glycol; polypropylene glycol;lower molecular weight polytetramethylene ether glycol;1,3-bis(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;resorcinol-di-(β-hydroxyethyl) ether; hydroquinone-di-(β-hydroxyethyl)ether; and mixtures thereof. Preferred hydroxy-terminated curativesinclude 1,3-bis-(2-hydroxyethoxy) benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}benzene;1,4-butanediol, and mixtures thereof. Preferably, the hydroxy-terminatedcuratives have molecular weights ranging from about 48 to 2000. Itshould be understood that molecular weight, as used herein, is theabsolute weight average molecular weight and would be understood as suchby one of ordinary skill in the art.

Both the hydroxy-terminated and amine curatives can include one or moresaturated, unsaturated, aromatic, and cyclic groups. Additionally, thehydroxy-terminated and amine curatives can include one or more halogengroups. The polyurethane composition can be formed with a blend ormixture of curing agents. If desired, however, the polyurethanecomposition may be formed with a single curing agent.

In a preferred embodiment of the present invention, saturatedpolyurethanes used to form cover layers, preferably the outer coverlayer, and may be selected from among both castable thermoset andthermoplastic polyurethanes.

In this embodiment, the saturated polyurethanes of the present inventionare substantially free of aromatic groups or moieties. Saturatedpolyurethanes suitable for use in the invention are a product of areaction between at least one polyurethane prepolymer and at least onesaturated curing agent. The polyurethane prepolymer is a product formedby a reaction between at least one saturated polyol and at least onesaturated diisocyanate. As is well known in the art, a catalyst may beemployed to promote the reaction between the curing agent and theisocyanate and polyol.

Saturated diisocyanates which can be used include, without limitation,ethylene diisocyanate; propylene-1,2-diisocyanate;tetramethylene-1,4-diisocyanate; 1,6-hexamethylene-diisocyanate (“HDI”);2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylenediisocyanate; dodecane-1,12-diisocyanate; dicyclohexylmethanediisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; isophoronediisocyanate (“IPDI”); methyl cyclohexylene diisocyanate ; triisocyanateof HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexane diisocyanate(“TMDI”). The most preferred saturated diisocyanates are4,4′-dicyclohexylmethane diisocyanate (“HMDI”) and isophoronediisocyanate (“IPDI”).

Saturated polyols which are appropriate for use in this inventioninclude without limitation polyether polyols such as polytetramethyleneether glycol and poly(oxypropylene) glycol. Suitable saturated polyesterpolyols include polyethylene adipate glycol, polyethylene propyleneadipate glycol, polybutylene adipate glycol, polycarbonate polyol andethylene oxide-capped polyoxypropylene diols. Saturated polycaprolactonepolyols which are useful in the invention include diethyleneglycol-initiated polycaprolactone, 1,4-butanediol-initiatedpolycaprolactone, 1,6-hexanediol-initiated polycaprolactone; trimethylolpropane-initiated polycaprolactone, neopentyl glycol initiatedpolycaprolactone, and polytetramethylene ether glycol-initiatedpolycaprolactone. The most preferred saturated polyols arepolytetramethylene ether glycol and PTMEG-initiated polycaprolactone.

Suitable saturated curatives include 1,4-butanediol, ethylene glycol,diethylene glycol, polytetramethylene ether glycol, propylene glycol;trimethanolpropane; tetra-(2-hydroxypropyl)-ethylenediamine; isomers andmixtures of isomers of cyclohexyldimethylol, isomers and mixtures ofisomers of cyclohexane bis(methylamine); triisopropanolamine; ethylenediamine; diethylene triamine; triethylene tetramine; tetraethylenepentamine; 4,4′-dicyclohexylmethane diamine;2,2,4-trimethyl-1,6-hexanediamine; 2,4,4-trimethyl-1,6-hexanediamine;diethyleneglycol di-(aminopropyl)ether;4,4′-bis-(sec-butylamino)-dicyclohexylmethane;1,2-bis-(sec-butylamino)cyclohexane; 1,4-bis-(sec-butylamino)cyclohexane; isophorone diamine; hexamethylene diamine; propylenediamine; 1-methyl-2,4-cyclohexyl diamine; 1-methyl-2,6-cyclohexyldiamine; 1,3-diaminopropane; dimethylamino propylamine; diethylaminopropylamine; imido-bis-propylamine; isomers and mixtures of isomers ofdiaminocyclohexane; monoethanolamine; diethanolamine; triethanolamine;monoisopropanolamine; and diisopropanolamine. The most preferredsaturated curatives are 1,4-butanediol, 1,4-cyclohexyldimethylol and4,4′-bis-(sec-butylamino)-dicyclohexylmethane.

Suitable catalysts include, but are not limited to bismuth catalyst,oleic acid, triethylenediamine (DABCO®-33LV), di-butyltin dilaurate(DABCO®-T12) and acetic acid. The most preferred catalyst is di-butyltindilaurate (DABCO®-T12). DABCO® materials are manufactured by AirProducts and Chemicals, Inc.

Thermoplastic materials may be blended with other thermoplasticmaterials, but thermosetting materials are difficult if not impossibleto blend homogeneously after the thermosetting materials are formed.Preferably, the saturated polyurethane comprises from about 1% to about100%, more preferably from about 10% to about 75% of the covercomposition and/or the intermediate layer composition. About 90% toabout 10%, more preferably from about 90% to about 25% of the coverand/or the intermediate layer composition is comprised of one or moreother polymers and/or other materials as described below. Such polymersinclude, but are not limited to polyurethane/polyurea ionomers,polyurethanes or polyureas, epoxy resins, polyethylenes, polyamides andpolyesters, polycarbonates and polyacrylin. Unless otherwise statedherein, all percentages are given in percent by weight of the totalcomposition of the golf ball layer in question.

Polyurethane prepolymers are produced by combining at least one polyol,such as a polyether, polycaprolactone, polycarbonate or a polyester, andat least one isocyanate. Thermosetting polyurethanes are obtained bycuring at least one polyurethane prepolymer with a curing agent selectedfrom a polyamine, triol or tetraol. Thermoplastic polyurethanes areobtained by curing at least one polyurethane prepolymer with a diolcuring agent. The choice of the curatives is critical because someurethane elastomers that are cured with a diol and/or blends of diols donot produce urethane elastomers with the impact resistance required in agolf ball cover. Blending the polyamine curatives with diol curedurethane elastomeric formulations leads to the production of thermoseturethanes with improved impact and cut resistance.

Thermoplastic polyurethanes may be blended with suitable materials toproduce a thermoplastic end product. Examples of such additionalmaterials may include ionomers such as the SURLYN®, ESCOR® and IOTEK®copolymers described above.

Other suitable materials which may be combined with the saturatedpolyurethanes in forming the cover and/or intermediate layer(s) of thegolf balls of the invention include ionic or non-ionic polyurethanes andpolyureas, epoxy resins, polyethylenes, polyamides and polyesters. Forexample, the cover and/or intermediate layer may be formed from a blendof at least one saturated polyurethane and thermoplastic or thermosetionic and non-ionic urethanes and polyurethanes, cationic urethaneionomers and urethane epoxies, ionic and non-ionic polyureas and blendsthereof. Examples of suitable urethane ionomers are disclosed in U.S.Pat. No. 5,692,974 entitled “Golf Ball Covers”, the disclosure of whichis hereby incorporated by reference in its entirety. Other examples ofsuitable polyurethanes are described in U.S. Pat. No. 5,334,673.Examples of appropriate polyureas are discussed in U.S. Pat. No.5,484,870 and examples of suitable polyurethanes cured with epoxy groupcontaining curing agents are disclosed in U.S. Pat. No. 5,908,358, thedisclosures of which are hereby incorporated herein by reference intheir entirety.

A variety of conventional components can be added to the covercompositions of the present invention. These include, but are notlimited to, white pigment such as TiO₂, ZnO, optical brighteners,surfactants, processing aids, foaming agents, density-controllingfillers, UV stabilizers and light stabilizers. Saturated polyurethanesare resistant to discoloration. However, they are not immune todeterioration in their mechanical properties upon weathering. Additionof UV absorbers and light stabilizers therefore helps to maintain thetensile strength and elongation of the saturated polyurethaneelastomers. Suitable UV absorbers and light stabilizers include TINUVIN®328, TINUVIN® 213, TINUVIN® 765, TINUVIN® 770 and TINUVIN® 622. Thepreferred UV absorber is TINUVIN® 328, and the preferred lightstabilizer is TINUVIN® 765. TINUVIN® products are available fromCiba-Geigy. Dyes, as well as optical brighteners and fluorescentpigments may also be included in the golf ball covers produced withpolymers formed according to the present invention. Such additionalingredients may be added in any amounts that will achieve their desiredpurpose.

Any method known to one of ordinary skill in the art may be used topolyurethanes of the present invention. One commonly employed method,known in the art as a one-shot method, involves concurrent mixing of thepolyisocyanate, polyol, and curing agent. This method results in amixture that is inhomogenous (more random) and affords the manufacturerless control over the molecular structure of the resultant composition.A preferred method of mixing is known as a prepolymer method. In thismethod, the polyisocyanate and the polyol are mixed separately prior toaddition of the curing agent. This method affords a more homogeneousmixture resulting in a more consistent polymer composition. Othermethods suitable for forming the layers of the present invention includereaction injection molding (“RIM”), liquid injection molding (“LIM”),and pre-reacting the components to form an injection moldablethermoplastic polyurethane and then injection molding, all of which areknown to one of ordinary skill in the art.

Additional components which can be added to the polyurethane compositioninclude UV stabilizers and other dyes, as well as optical brightenersand fluorescent pigments and dyes. Such additional ingredients may beadded in any amounts that will achieve their desired purpose. It hasbeen found by the present invention that the use of a castable, reactivematerial, which is applied in a fluid form, makes it possible to obtainvery thin outer cover layers on golf balls. Specifically, it has beenfound that castable, reactive liquids, which react to form a urethaneelastomer material, provide desirable very thin outer cover layers.

The castable, reactive liquid employed to form the urethane elastomermaterial can be applied over the core using a variety of applicationtechniques such as spraying, dipping, spin coating, or flow coatingmethods which are well known in the art. An example of a suitablecoating technique is that which is disclosed in U.S. Pat. No. 5,733,428,the disclosure of which is hereby incorporated by reference in itsentirety.

The outer cover is preferably formed around the inner cover by mixingand introducing the material in the mold halves. It is important thatthe viscosity be measured over time, so that the subsequent steps offilling each mold half, introducing the core into one half and closingthe mold can be properly timed for accomplishing centering of the corecover halves fusion and achieving overall uniformity. Suitable viscosityrange of the curing urethane mix for introducing cores into the moldhalves is determined to be approximately between about 2,000 cP andabout 30,000 cP, with the preferred range of about 8,000 cP to about15,000 cP.

To start the cover formation, mixing of the prepolymer and curative isaccomplished in motorized mixer including mixing head by feeding throughlines metered amounts of curative and prepolymer. Top preheated moldhalves are filled and placed in fixture units using centering pinsmoving into holes in each mold. At a later time, a bottom mold half or aseries of bottom mold halves have similar mixture amounts introducedinto the cavity. After the reacting materials have resided in top moldhalves for about 40 to about 80 seconds, a core is lowered at acontrolled speed into the gelling reacting mixture.

A ball cup holds the ball core through reduced pressure (or partialvacuum). Upon location of the coated core in the halves of the moldafter gelling for about 40 to about 80 seconds, the vacuum is releasedallowing core to be released. The mold halves, with core and solidifiedcover half thereon, are removed from the centering fixture unit,inverted and mated with other mold halves which, at an appropriate timeearlier, have had a selected quantity of reacting polyurethaneprepolymer and curing agent introduced therein to commence gelling.

Similarly, U.S. Pat. No. 5,006,297 to Brown et al. and U.S. Pat. No.5,334,673 to Wu both also disclose suitable molding techniques which maybe utilized to apply the castable reactive liquids employed in thepresent invention. Further, U.S. Pat. Nos. 6,180,040 and 6,180,722disclose methods of preparing dual core golf balls. The disclosures ofthese patents are hereby incorporated by reference in their entirety.However, the method of the invention is not limited to the use of thesetechniques.

Depending on the desired properties, balls prepared according to theinvention can exhibit substantially the same or higher resilience, orcoefficient of restitution (“COR”), with a decrease in compression ormodulus, compared to balls of conventional construction. Additionally,balls prepared according to the invention can also exhibit substantiallyhigher resilience, or COR, without an increase in compression, comparedto balls of conventional construction. Another measure of thisresilience is the “loss tangent,” or tan δ, which is obtained whenmeasuring the dynamic stiffness of an object. Loss tangent andterminology relating to such dynamic properties is typically describedaccording to ASTM D4092-90. Thus, a lower loss tangent indicates ahigher resiliency, thereby indicating a higher rebound capacity. Lowloss tangent indicates that most of the energy imparted to a golf ballfrom the club is converted to dynamic energy, i.e., launch velocity andresulting longer distance. The rigidity or compressive stiffness of agolf ball may be measured, for example, by the dynamic stiffness. Ahigher dynamic stiffness indicates a higher compressive stiffness. Toproduce golf balls having a desirable compressive stiffness, the dynamicstiffness of the crosslinked reaction product material should be lessthan about 50,000 N/m at −50° C. Preferably, the dynamic stiffnessshould be between about 10,000 and 40,000 N/m at −50° C., morepreferably, the dynamic stiffness should be between about 20,000 and30,000 N/m at −50° C.

The molding process and composition of golf ball portions typicallyresults in a gradient of material properties. Methods employed in theprior art generally exploit hardness to quantify these gradients.Hardness is a qualitative measure of static modulus and does notrepresent the modulus of the material at the deformation ratesassociated with golf ball use, i.e., impact by a club. As is well knownto one skilled in the art of polymer science, the time-temperaturesuperposition principle may be used to emulate alternative deformationrates. For golf ball portions including polybutadiene, a 1-Hzoscillation at temperatures between 0° C. and −50° C. are believed to bequalitatively equivalent to golf ball impact rates. Therefore,measurement of loss tangent and dynamic stiffness at 0° C. to −50° C.may be used to accurately anticipate golf ball performance, preferablyat temperatures between about −20° C. and −50° C.

Referring to FIG. 3, in another embodiment of the present invention, agolf ball 5 of the present invention is substantially spherical and hasa cover 25 with a plurality of dimples 27 formed on the outer surfacethereof.

Referring to FIGS. 4-6, the golf ball 5 includes an inner core 10, anouter core 15 and 20, and the cover 25 (shown without dimples). Theinner core 10 includes a three-dimensional outer surface 28, a center C,a central portion 30, and a plurality of projections 35. The centralportion 30 and projections 35 are integrally formed, so that the innercore is a single piece.

Referring to FIG. 6, the outer surface 28 of the inner core is definedby radial distances from the center C. At least two of the radialdistances about the outer surface are different. The central portion 30has a radius, designated by the arrow r_(cp), that extends from the corecenter C to the outer surface of the central portion. The centralportion 30 is solid in this embodiment.

Referring to FIGS. 5 and 6, each of the projections 35 extend radiallyoutwardly from the central portion 30, and are spaced from one anotherto define gaps 40 there between. The projections 35 are shaped so thatthe inner core 10 is substantially spherically symmetrical.

Each projection 35 has an enlarged free end 45 and a substantiallyconical shape. Each free end 45 includes an open recess 50. Eachprojection has a radius, designated by the arrow r_(p), that extendsfrom the core center C to the outer surface 28 at the free end 45. Theprojection radii r_(p) differ from the central portion radius r_(cp).

Referring to FIG. 5, each recess 50 is formed by three integral sidewalls 55. Each of the side walls 55 is shaped like a flat quartercircle. The quarter circle includes two straight edges 60 joined by acurved edge 65. In each projection 35, each of the side walls 55 isjoined at the straight edges 60. The curved edges 65 of each of theprojections allow the inner core to have a spherical shape.

With reference to a three-dimensional Cartesian Coordinate system, thereare perpendicular x, y, and z axes, respectively that form eightoctants. There are eight projections 35 with one in each octant of thecoordinate system, so that each of the projections 35 forms an octant ofthe skeletal sphere. Thus, the inner core is symmetrical. The gaps 40define three perpendicular concentric rings 70 _(x), 70 _(y), and 70_(z). The subscript for the reference number 70 designates the centralaxis of the ring about which the ring circumscribes.

Turning to FIGS. 4 and 6, the outer core includes a first section 15 anda second section 20. The first section 15 fills the gaps 40 around theprojections 35, and is disposed between the side walls 55 of adjacentprojections 35. It is preferred that the diameter of the core whichincludes the inner core and the outer core is between about 1.00 inchesand about 1.64 inches for a ball having a diameter of 1.68 inches.

The second section 20 fills the recesses 50 of each projection 35, andis disposed between the side walls 55 of a single projection 35. Theouter core is formed so that the outer core terminates flush with thefree end 45 of each projection 35. The outer core has a substantiallyspherical outer surface. The cover 25 is formed about the inner core 10and the outer core sections 15 and 20, so that both the inner and outercores abut the cover.

Referring to FIG. 4, the formation of a golf ball starts with formingthe inner core 10. The inner core 10, outer core sections 15 and 20, andthe cover 25 are formed by compression molding, by injection molding, orby casting. These methods of forming cores and covers of this type arewell known in the art.

The materials used for the inner and outer core, as well as the cover,are selected so that the desired playing characteristics of the ball areachieved. The inner and outer core materials have substantiallydifferent material properties so that there is a predeterminedrelationship between the inner and outer core materials, to achieve thedesired playing characteristics of the ball.

In one embodiment, the inner core is formed of a first material having afirst Shore D hardness, a first elastic modulus, a first specificgravity, and a first Bashore resilience. The outer core is formed of asecond material having a second Shore D hardness, a second elasticmodulus, a second specific gravity, and a second Bashore resilience.Preferably, the material property of the first material equals at leastone selected from the group consisting of the first Shore D hardnessdiffering from the second Shore D hardness by at least 10 points, thefirst elastic modulus differing from the second elastic modulus by atleast 10%, the first specific gravity differing from the second specificgravity by at least 0.1, or a first Bashore resilience differing fromthe second Bashore resilience by at least 10%. It is more preferred thatthe first material have all of these material property relationships.

Moreover, it is preferred that the first material has the first Shore Dhardness between about 30 and about 80, the first elastic modulusbetween about 5,000 psi and about 100,000 psi, the first specificgravity between about 0.8 and about 1.6, and the first Bashoreresilience greater than 30%.

In another embodiment, the first Shore D hardness is less than thesecond Shore D hardness, the first elastic modulus is less than thesecond elastic modulus, the first specific gravity is less than thesecond specific gravity, and the first Bashore resilience is less thanthe second Bashore resilience. In another embodiment, the first materialproperties are greater than the second material properties. Therelationship between the first and second material properties depends onthe desired playability characteristics.

Suitable inner and outer core materials include HNP's neutralized withorganic fatty acids and salts thereof, metal cations, or a combinationof both, thermosets, such as rubber, polybutadiene, polyisoprene;thermoplastics, such as ionomer resins, polyamides or polyesters; orthermoplastic elastomers. Suitable thermoplastic elastomers includePEBAX®, HYTREL®, thermoplastic urethane, and KRATON®, which arecommercially available from Elf-Atochem, DuPont, B F Goodrich, andShell, respectively. The inner and outer core materials can also beformed from a castable material. Suitable castable materials include,but are not limited to, urethane, urea, epoxy, diols, or curatives.

The cover 25 is selected from conventional materials used as golf ballcovers based on the desired performance characteristics. The cover maybe comprised of one or more layers. Cover materials such as ionomerresins, blends of ionomer resins, thermoplastic or thermoset urethanes,and balata, can be used as known in the art and discussed above.

Referring to FIG. 7, another embodiment of the golf ball 505 is shown.Similar structures to those discussed above use the same referencenumber preceded with the numeral “5.” The golf ball 505 includes anouter core with a first section 515 and a second section 520. The firstsection 515 and the second section 520 are formed of two materials withdifferent material properties. In this embodiment, the core includesthree different materials.

Referring to FIG. 8, another embodiment of the golf ball 605 is shown.Similar structures to those discussed above use the same referencenumber preceded with the numeral “6.” The golf ball 605 includes anintermediate layer 612 disposed between the cover 625 and the inner core610 and outer cores 615 and 620. The intermediate layer 612 is formed ofeither outer core material, cover material, or a different material. Thefirst section 615 and the second section 620 of the outer core areformed of materials with the same material properties. However, inanother embodiment, sections 615 and 620 can be formed of differentmaterials. The intermediate layer 612 covers the inner core 610, outercore 615 and 620, and forms a continuous layer beneath the cover 625.

Referring to FIG. 9, another embodiment of the golf ball 705 is shown.Similar structures to those discussed above use the same referencenumber preceded with the numeral “7.” The golf ball 705 includes anintermediate layer 712 disposed between the cover 725 and the inner core710 and outer cores 715 and 720. The intermediate layer 712 is formed ofeither outer core material, cover material or a different material. Thefirst section 715 and the second section 720 of the outer core areformed of materials with different material properties. The intermediatelayer 712 covers the inner core 710, outer core 715 and 720, and forms acontinuous layer beneath the cover 725.

Referring to FIG. 10, another embodiment of the golf ball 805 is shown.Similar structures to those discussed above use the same referencenumber preceded with the numeral “8.” The golf ball 805 includes anouter core with a multi-material first section 815 a and 815 b disposedwithin the gaps 840. The different portions 815 a, 815 b of the firstsection of the outer core are formed of two materials with differentmaterial properties.

In other embodiments, additional layers may be added to those mentionedabove or the existing layers may be formed by multiple materials.

Referring to FIG. 11, another embodiment of the golf ball 905 is shown.Similar structures to those discussed above use the same referencenumber preceded with the numeral “9.” The golf ball 905 includes aninner core 910 including a central portion 930 and a plurality ofoutwardly radially extending projections 935. The central portion 930 ishollow to define a chamber 990 therein. The outer core is formed from afirst section 915 disposed within the gaps 940, and a second section 920disposed within the recesses 950. The first section and the secondsection are formed of material with the same material properties. Thecover section 925 surrounds the outer core 915 and 920. The hollowcentral portion 930 reduces the volume of the inner core 910 material.The central portion may include a fluid.

Referring to FIG. 12, another embodiment of the golf ball 1005 is shown.Similar structures to those discussed above use the same referencenumber preceded with the numeral “10.” The golf ball 1005 includes aninner core 1010 and an outer core 1015, 1020. The inner core 1010includes a central portion 1030 and a plurality of outwardly radiallyextending projections 1035. The central portion 1030 is hollow andsurrounds a fluid-filled center 1095. The fluid-filled center 1095 isformed of an envelope 1096 containing a fluid 1097. The outer core isformed from a first section 1015 disposed within the gaps 1040, and asecond section 1020 disposed within the recesses 1050. The first sectionand the second section are formed of material with the same materialproperties. The cover material 1025 surrounds the inner and outer cores.

Referring to FIG. 12, when the core is formed with a fluid-filled center1095, the center is formed first then the inner core 1020 is moldedaround the center. Conventional molding techniques can be used for thisoperation. Then the outer core 1015, 1020 and cover 1025 are formedthereon, as discussed above.

Referring to FIGS. 11 and 12, the fluid within the inner core can be awide variety of materials including air, water solutions, liquids, gels,foams, hot-melts, other fluid materials and combinations thereof. Thefluid is varied to modify the performance parameters of the ball, suchas the moment of inertia or the spin decay rate.

Examples of suitable liquids include either solutions such as salt inwater, corn syrup, salt in water and corn syrup, glycol and water oroils. The liquid can further include pastes, colloidal suspensions, suchas clay, barytes, carbon black in water or other liquid, or salt inwater/glycol mixtures. Examples of suitable gels include water gelatingels, hydrogels, water/methyl cellulose gels and gels comprised ofcopolymer rubber based materials such a styrene-butadiene-styrene rubberand paraffinic and/or naphthenic oil. Examples of suitable melts includewaxes and hot melts. Hot-melts are materials which at or about normalroom temperatures are solid but at elevated temperatures become liquid.A high melting temperature is desirable since the liquid core is heatedto high temperatures during the molding of the inner core, outer core,and the cover. The liquid can be a reactive liquid system, whichcombines to form a solid. Examples of suitable reactive liquids aresilicate gels, agar gels, peroxide cured polyester resins, two partepoxy resin systems and peroxide cured liquid polybutadiene rubbercompositions.

Referring to FIG. 13, another embodiment of an inner core 2010 is shown.The inner core 2010 includes a spherical central portion 2030 having anouter surface 2031, and a plurality of projections 2035 extendingradially outwardly from the central portion 2030. The projections 2035include a base 2036 adjacent the outer surface 2031 and a pointed freeend 2038. The projections 2035 are substantially conical and taper fromthe base 2036 to the pointed free end 2038. It is preferred that thebases cover greater than about 15% of the outer surface. Morepreferably, the bases should cover greater than about 50% of the outersurface. Most preferably, the bases should be circular in shape andcover greater than about 80% of the outer surface and less than about85%. As a result, the projections 2035 are spaced from one another andthe area of the outer surface 2031 between each projection base 2036 isless than the area of each base. The projections 2035 are conical andconfigured so that the free ends 2038 of the projections form aspheroid. The base can have other shapes, such as polygons. Examples ofpolygon shapes that can be used for the base are triangles, pentagons,and hexagons. In addition, instead of the projections having a circularcross-section they can have other cross-sectional shapes such as square.

The projections further include a base diameter, designated by theletter d, and a projection height, designated by the letter h. It ispreferred that the base diameter d is greater than or equal to theprojection height h. This allows an included angle α between twodiametrically opposed sides of the projection, designated L1 and L2, tobe about 60° or more. More preferably the angle α is about 90° or moreand most preferably the angle α is about 135°. This allows a simple moldto be used from which the core can be extracted.

To form a golf ball with inner core 2010 an outer core, as discussedabove, is disposed around the inner core 2010 so that the outer corematerial is disposed within the gaps 2040 and the outer surface of theouter core is substantially spherical. The materials for the inner andouter cores are as discussed above. Then, the cover is formed thereon.The outer surface of the inner core has non-uniform radial distancesfrom the center to various locations on the outer surface due to theconical projections 2035.

Referring to FIG. 14, another embodiment of an inner core 3010 is shown.The inner core outer surface 3020 includes a plurality of projections3035 formed so that gaps 3040 are formed surrounding each projection andbetween projections. Each projection includes a maximum length, which isthe longest length of the projection, designated L. Each projection alsoincludes a maximum width, which is the widest width of the projection,designated W. The surface of the projection is curved along the length Land width W. A substantial number of projections have the maximum lengthgreater than the maximum width so that the projections are elongated. Toform a golf ball, an outer core, as discussed above, is disposed aroundthe inner core 3010 so that the outer core material is disposed withinthe gaps. The outer core material forms a substantially sphericalsurface. The materials for the inner and outer cores are as discussedabove. Then a cover is formed thereon. The outer surface of the innercore has non-uniform radial distances from the center due to theprojections and the indentations.

In this embodiment, in order to form the outer surface of this innercore, first, second and third surfaces are formed by rotation of a waveform about first, second and third axes, respectively. These axii arethe x-, y- and z-axii in a Cartesian Coordinate System. The wave formused is sine wave. However, other wave forms can be used including, butnot limited to, cosine or saw-tooth wave forms.

Referring to FIG. 15, an inner core 4010, similar to that shown in FIG.14, is illustrated. The inner core outer surface 4020 includes aplurality of projections 4035 formed so that gaps 4040 are formedsurrounding each projection and between projections. Each projectionincludes a maximum length, which is the longest length of theprojection, designated L. Each projection also includes a maximum width,which is the widest width of the projection, designated W. The surfaceof the projection is curved along the length L and width W. Asubstantial number of projections have the maximum length greater thanthe maximum width so that the projections are elongated.

In this embodiment, in order to form the outer surface of this innercore, the first, second, and third surfaces are formed as discussedabove, and a fourth surface that is formed by rotating the wave formabout a fourth axis that is about 45° from the first and second axii.The surface of the inner core 4020 is formed by the intersection of thefirst, second, third and fourth surfaces. Any number of surfaces greaterthan three can be used to create different outer surface geometries forthe inner core. Furthermore, different axii can also be used.

In all the embodiments, there is a characteristic of the core that iscalled the “transition volume,” which will now be discussed. Referringto FIG. 4, the ball 5 has a radius r_(IC) that includes only inner corematerial. The ball further an outer core and inner core radius r_(OCIC)that includes both the inner core material and the outer core material.A transition radius is the outer core and inner core radius r_(OCIC)less the inner core radius r_(IC). The transition volume is the volumethat is calculated when the transition radius is used. Thus, thetransition volume is the volume of the golf ball that contains bothinner core and outer core material therein, and it is an annular sector.The total volume of the core is the volume of all of the inner corematerial plus the volume of all of the outer core material. Favorablecores have been formed when the transition volume is at least 10% of thetotal core volume.

The “effective compression constant,” which is designated EC, is theratio of deflection of a 1.50 inch diameter sphere made of any singlematerial used in the core under a 100 kg load that as represented by theformula EC=F/d, where, F is a 100 kg load; and d is the deflection inmillimeters.

If the sphere tested is only inner core material, the effectivecompression constant for the inner core material alone is designatedEC_(IC). If the sphere tested is only outer core material, the effectivecompression constant for the outer core material alone is designatedEC_(OC). The sum of the constants for the inner core EC_(IC) and outercore EC_(OC) is the constant EC_(S). If the sphere tested is inner andouter core material, the core effective compression constant isdesignated EC_(C).

It is has been determined that very favorable cores are formed whentheir core effective compression constant EC_(C) is less than the sum ofthe effective compression constants of the inner core and outer coreEC_(S). It is recommended that the core effective compression constantEC_(C) is less than about 90% of the sum of the effective compressionconstants of the inner core and outer core EC_(S). More preferably, thecore effective compression constant EC_(C) is less than or equal toabout 50% of the sum of the effective compression constants of the innercore and outer core EC_(S). The ratios of the inner core material toouter core material and the geometry of the inner core to the outer coreare selected to achieve these core effective compression constants.

The resultant golf balls typically have a coefficient of restitution ofgreater than about 0.7, preferably greater than about 0.75, and morepreferably greater than about 0.78. The golf balls also typically havean Atti compression of at least about 40, preferably from about 50 to120, and more preferably from about 60 to 100. The golf ball curedpolybutadiene material typically has a hardness of at least about 15Shore A, preferably between about 30 Shore A and 80 Shore D, morepreferably between about 50 Shore A and 60 Shore D.

In addition to the HNP's neutralized with organic fatty acids and saltsthereof, core compositions may comprise at least one rubber materialhaving a resilience index of at least about 40. Preferably theresilience index is at least about 50. Polymers that produce resilientgolf balls and, therefore, are suitable for the present invention,include but are not limited to CB23, CB22, commercially available fromof Bayer Corp. of Orange, Tex., BR60, commercially available fromEnichem of Italy, and 1207G, commercially available from Goodyear Corp.of Akron, Ohio.

Additionally, the unvulcanized rubber, such as polybutadiene, in golfballs prepared according to the invention typically has a Mooneyviscosity of between about 40 and about 80, more preferably, betweenabout 45 and about 65, and most preferably, between about 45 and about55. Mooney viscosity is typically measured according to ASTM-D1646.

When golf balls are prepared according to the invention, they typicallywill have dimple coverage greater than about 60 percent, preferablygreater than about 65 percent, and more preferably greater than about 75percent. The flexural modulus of the cover on the golf balls, asmeasured by ASTM method D6272-98, Procedure B, is typically greater thanabout 500 psi, and is preferably from about 500 psi to 150,000 psi. Asdiscussed herein, the outer cover layer is preferably formed from arelatively soft polyurethane material. In particular, the material ofthe outer cover layer should have a material hardness, as measured byASTM-D2240, less than about 45 Shore D, preferably less than about 40Shore D, more preferably between about 25 and about 40 Shore D, and mostpreferably between about 30 and about 40 Shore D. The casing preferablyhas a material hardness of less than about 70 Shore D, more preferablybetween about 30 and about 70 Shore D, and most preferably, betweenabout 50 and about 65 Shore D.

In a preferred embodiment, the intermediate layer material hardness isbetween about 40 and about 70 Shore D and the outer cover layer materialhardness is less than about 40 Shore D. In a more preferred embodiment,a ratio of the intermediate layer material hardness to the outer coverlayer material hardness is greater than 1.5.

It should be understood, especially to one of ordinary skill in the art,that there is a fundamental difference between “material hardness” and“hardness, as measured directly on a golf ball.” Material hardness isdefined by the procedure set forth in ASTM-D2240 and generally involvesmeasuring the hardness of a flat “slab” or “button” formed of thematerial of which the hardness is to be measured. Hardness, whenmeasured directly on a golf ball (or other spherical surface) is acompletely different measurement and, therefore, results in a differenthardness value. This difference results from a number of factorsincluding, but not limited to, ball construction (i.e., core type,number of core and/or cover layers, etc.), ball (or sphere) diameter,and the material composition of adjacent layers. It should also beunderstood that the two measurement techniques are not linearly relatedand, therefore, one hardness value cannot easily be correlated to theother.

In one embodiment, the core of the present invention has an Atticompression of between about 50 and about 90, more preferably, betweenabout 60 and about 85, and most preferably, between about 65 and about85. The overall outer diameter (“OD”) of the core is less than about1.590 inches, preferably, no greater than 1.580 inches, more preferablybetween about 1.540 inches and about 1.580 inches, and most preferablybetween about 1.525 inches to about 1.570 inches. The OD of the casingof the golf balls of the present invention is preferably between 1.580inches and about 1.640 inches, more preferably between about 1.590inches to about 1.630 inches, and most preferably between about 1.600inches to about 1.630 inches.

The present multilayer golf ball can have an overall diameter of anysize. Although the United States Golf Association (“USGA”)specifications limit the minimum size of a competition golf ball to1.680 inches. There is no specification as to the maximum diameter. Golfballs of any size, however, can be used for recreational play. Thepreferred diameter of the present golf balls is from about 1.680 inchesto about 1.800 inches. The more preferred diameter is from about 1.680inches to about 1.760 inches. The most preferred diameter is about 1.680inches to about 1.740 inches.

The golf balls of the present invention should have a moment of inertia(“MOI”) of less than about 85 and, preferably, less than about 83. TheMOI is typically measured on model number MOI-005-104 Moment of InertiaInstrument manufactured by Inertia Dynamics of Collinsville, Conn. Theinstrument is plugged into a PC for communication via a COMM port and isdriven by MOI Instrument Software version #1.2.

U.S. Pat. Nos. 6,193,619; 6,207,784; and 6,221,960, and U.S. applicationSer. Nos. 09/594,031, filed Jun. 15, 2000; 09/677,871, filed Oct. 3,2000, and 09/447,652, filed Nov. 23, 1999, are incorporated in theirentirety herein by express reference thereto.

The highly-neutralized polymers of the present invention may also beused in golf equipment, in particular, inserts for golf clubs, such asputters, irons, and woods, and in golf shoes and components thereof.

As used herein, the term “about,” used in connection with one or morenumbers or numerical ranges, should be understood to refer to all suchnumbers, including all numbers in a range.

The invention described and claimed herein is not to be limited in scopeby the specific embodiments herein disclosed, since these embodimentsare intended solely as illustrations of several aspects of theinvention. Any equivalent embodiments are intended to be within thescope of this invention. Indeed, various modifications of the inventionin addition to those shown and described herein will become apparent tothose skilled in the art from the foregoing description. Suchmodifications are also intended to fall within the scope of the appendedclaims.

What is claimed is:
 1. A golf ball comprising: an inner core formed of afirst material and comprising: i) a central portion; and ii) a pluralityof spaced projections extending radially outward from the centralportion forming gaps between each projection, and each projection havingan enlarged free end and a generally conical shape; an outer core formedof a second material, said second material being disposed within thegaps to form a core; and a cover layer; wherein at least one of thefirst and second materials comprises a first polymer containing an acidgroup neutralized by a salt of an organic acid, a cation source, or asuitable base of the organic acid, the salt of the organic acid, thecation source, or the suitable base of the organic acid being present inan amount sufficient to neutralize the polymer by no less than about100%.
 2. The golf ball of claim 1, wherein the first polymer is blendedwith a second polymer, wherein the second polymer comprises ionomericcopolymers and terpolymers, ionomer precursors, thermoplastics,thermoplastic elastomers, polybutadiene rubber, balata, graftedmetallocene-catalyzed polymers, non-grafted metallocene-catalyzedpolymers, single-site polymers, high-crystalline acid polymers, orcationic ionomers.
 3. The golf ball of claim 1, wherein the organic acidis selected from the group consisting of aliphatic organic acids,aromatic organic acids, saturated mono-functional organic acids,unsaturated mono-functional organic acids, and multi-unsaturatedmono-functional organic acids.
 4. The golf ball of claim 1, wherein thesalt of organic acids comprises the salts of barium, lithium, sodium,zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium,tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, andcalcium.
 5. The golf ball of claim 1, wherein the spaced projections areconfigured to from an octet skeletal sphere.
 6. The golf ball of claim1, wherein the golf ball further comprises intermediate layer disposedbetween the outer core and inner core or the cover layer.
 7. The golfball of claim 6, wherein the intermediate layer forms a continuous layerbeneath the cover layer.
 8. The golf ball of claim 1, wherein the firstand second materials have substantially different material properties.9. The golf ball of claim 1, wherein the first material has a firstShore D hardness and a first flexural modulus less and the secondmaterial has a second Shore D hardness and a second flexural modulusgreater than the first.
 10. The golf ball of claim 1, wherein the firstmaterial has a Shore D hardness between about 30 and about 80 and anelastic modulus between about 5,000 psi and about 100,000 psi.
 11. Thegolf ball of claim 1, wherein the first material comprises thefully-neutralized polymer and the second material comprises thermosetmaterials selected from the group consisting of rubbers, polybutadienes,and polyisoprenes; thermoplastic materials selected from the groupconsisting of ionomers, polyamides, polyesters, and thermoplasticelastomers; or castable materials selected from the group consisting ofurethanes, ureas, epoxies, diols, and curatives.
 12. The golf ball ofclaim 1, wherein the inner or outer core has a diameter of about 1.58inches or greater.
 13. The golf ball of claim 1, wherein the cover iscomprised of a castable reactive liquid material.
 14. The golf ball ofclaim 1, wherein the cover is cast or reaction injection molded over thecore.
 15. The golf ball of claim 1, wherein the cover is comprised of apolyurethane, a polyurea, or a hybrid of both.
 16. A golf ballcomprising: an inner core of a thermoset rubber and comprising: aspherical central portion having an outer surface; and a plurality ofprojections extending radially outward from the central portion, saidprojections having a base adjacent the outer surface, a free end, andeach projection tapers from the base toward the free end, and each basebeing circular or conical, and each base having a diameter greater thanthe height of the projection; a non-wound outer core comprised of apolymer neutralized with a salt of an organic acid, a cation source, ora suitable base of the organic acid, the salt of organic acid, thecation source, or the suitable base of the organic acid being present inan amount greater than about 10 weight percent such that the polymer isfully neutralized, and being disposed around the inner core to form acore so that the outer surface of the outer core has a compression ofless than or equal to about 90 and a diameter of about 1.53 inches orgreater; and a cover surrounding the inner core and the outer core, thecover comprising a castable reactive liquid material.
 17. The golf ballof claim 16, wherein the bases cover greater than about 15% of the outersurface.
 18. The golf ball of claim 16, wherein the bases cover greaterthan about 50% of the outer surface.
 19. The golf ball of claim 16,wherein the bases cover greater than about 80% of the outer surface. 20.A golf ball comprising: an inner core comprised of a first polymerneutralized with a salt of an organic acid, a cation source, or asuitable base of the organic acid, the organic acid salt the cationsource, or the suitable base of the organic acid being present in anamount greater than about 10 weight percent such that the polymer isfully neutralized and including a substantially spherical outer surfacethat includes a plurality of projections formed so that gaps are formedsurrounding each projection, and the projections having a maximum lengthgreater than the maximum width; an outer core formed of a secondmaterial and being disposed around the inner core to form a core; and acover surrounding the outer core.
 21. The golf ball of claim 20, whereinthe surface of the inner core is described by the intersection of afirst surface, a second surface, and a third surface, the first surfacebeing formed by rotation of a wave form about a first axis, the secondsurface being formed by rotation of the wave form about a second axis,and the third surface being formed by rotation of a wave form about athird axis.
 22. The golf ball of claim 21, wherein the surface of theinner core is described by the intersection of the first surface, thesecond surface, the third surface, and a fourth surface, the fourthsurface being formed by rotation of the wave form about a fourth axisthat is about 45° between the first and second axii.
 23. The golf ballof claim 20, wherein the first polymer is blended with a second polymer,wherein the second polymer comprises ionomeric copolymers andterpolymers, ionomer precursors, thermoplastics, thermoplasticelastomers, polybutadiene rubber, balata, grafted metallocene-catalyzedpolymers, non-grafted metallocene-catalyzed polymers, single-sitepolymers, high-crystalline acid polymers, or cationic ionomers.
 24. Thegolf ball of claim 23, wherein the second polymer is neutralized by asalt of an organic acid, a cation source, or a suitable base of theorganic acid, the organic acid salt, the cation source, or the suitablebase of the organic acid being present in an amount sufficient toneutralize the second material by at least about 90%.
 25. The golf ballof claim 24, wherein the second polymer is neutralized by no less thanabout 100%.
 26. A golf ball comprising: an inner core comprised of apolymer neutralized with a salt of an organic acid, a cation source, ora suitable base of the organic acid, the organic acid salt, the cationsource, or the suitable base of the organic acid being present in amountgreater than about 10 weight percent such that the polymer is fullyneutralized and including a substantially spherical outer surface thatincludes a plurality of projections formed so that gaps are formedsurrounding each projection, and the projections having a maximum lengthgreater than the maximum width; an outer core formed of a secondmaterial and being disposed around the inner core to form a core; and acover surrounding the outer core; wherein the core has an effectivecompression constant less than a sum of an inner core effectivecompression constant and an outer core effective compression constant.